diff --git a/cura/Machines/MaterialManager.py b/cura/Machines/MaterialManager.py
index 264f7bbd8b..dc9fb55902 100644
--- a/cura/Machines/MaterialManager.py
+++ b/cura/Machines/MaterialManager.py
@@ -131,8 +131,8 @@ class MaterialManager(QObject):
 
         # Fetch the available materials (ContainerNode) for the current active machine and extruder setup.
         materials = self.getAvailableMaterials(machine.definition.getId(), nozzle_name)
-        compatible_material_diameter = str(round(extruder_stack.getCompatibleMaterialDiameter()))
-        result = {key: material for key, material in materials.items() if material.container and material.container.getMetaDataEntry("approximate_diameter") == compatible_material_diameter}
+        compatible_material_diameter = extruder_stack.getApproximateMaterialDiameter()
+        result = {key: material for key, material in materials.items() if material.container and float(material.container.getMetaDataEntry("approximate_diameter")) == compatible_material_diameter}
         return result
 
     #
@@ -171,9 +171,11 @@ class MaterialManager(QObject):
     def getMaterialNodeByType(self, global_stack: "GlobalStack", position: str, nozzle_name: str,
                               buildplate_name: Optional[str], material_guid: str) -> Optional["MaterialNode"]:
         machine_definition = global_stack.definition
-        variant_name = global_stack.extruders[position].variant.getName()
+        extruder = global_stack.extruderList[int(position)]
+        variant_name = extruder.variant.getName()
+        approximate_diameter = extruder.getApproximateMaterialDiameter()
 
-        return self.getMaterialNode(machine_definition.getId(), variant_name, buildplate_name, 3, material_guid)
+        return self.getMaterialNode(machine_definition.getId(), variant_name, buildplate_name, approximate_diameter, material_guid)
 
     #   There are 2 ways to get fallback materials;
     #   - A fallback by type (@sa getFallbackMaterialIdByMaterialType), which adds the generic version of this material
@@ -266,128 +268,59 @@ class MaterialManager(QObject):
                 return False
         return True
 
+    ##  Change the user-visible name of a material.
+    #   \param material_node The ContainerTree node of the material to rename.
+    #   \param name The new name for the material.
     @pyqtSlot("QVariant", str)
     def setMaterialName(self, material_node: "MaterialNode", name: str) -> None:
-        if material_node.container is None:
-            return
-        root_material_id = material_node.container.getMetaDataEntry("base_file")
-        if root_material_id is None:
-            return
-        if CuraContainerRegistry.getInstance().isReadOnly(root_material_id):
-            Logger.log("w", "Cannot set name of read-only container %s.", root_material_id)
-            return
-        containers = CuraContainerRegistry.getInstance().findInstanceContainers(id = root_material_id)
-        containers[0].setName(name)
+        return cura.CuraApplication.CuraApplication.getMaterialManagementModel().setMaterialName(material_node, name)
 
+    ##  Deletes a material from Cura.
+    #
+    #   This function does not do any safety checking any more. Please call this
+    #   function only if:
+    #   - The material is not read-only.
+    #   - The material is not used in any stacks.
+    #   If the material was not lazy-loaded yet, this will fully load the
+    #   container. When removing this material node, all other materials with
+    #   the same base fill will also be removed.
+    #   \param material_node The material to remove.
     @pyqtSlot("QVariant")
     def removeMaterial(self, material_node: "MaterialNode") -> None:
-        if material_node.container is None:
-            return
-        root_material_id = material_node.container.getMetaDataEntry("base_file")
-        if root_material_id is not None:
-            self.removeMaterialByRootId(root_material_id)
+        return cura.CuraApplication.CuraApplication.getMaterialManagementModel().setMaterialName(material_node)
 
-    def duplicateMaterialByRootId(self, root_material_id: str, new_base_id: Optional[str] = None,
-                                  new_metadata: Optional[Dict[str, Any]] = None) -> Optional[str]:
-        container_registry = CuraContainerRegistry.getInstance()
-        results = container_registry.findContainers(id=root_material_id)
-
-        if not results:
-            Logger.log("i", "Unable to duplicate the material with id %s, because it doesn't exist.", root_material_id)
-            return None
-
-        base_container = results[0]
-
-        # Ensure all settings are saved.
-        cura.CuraApplication.CuraApplication.getInstance().saveSettings()
-
-        # Create a new ID & container to hold the data.
-        new_containers = []
-        if new_base_id is None:
-            new_base_id = container_registry.uniqueName(base_container.getId())
-        new_base_container = copy.deepcopy(base_container)
-        new_base_container.getMetaData()["id"] = new_base_id
-        new_base_container.getMetaData()["base_file"] = new_base_id
-        if new_metadata is not None:
-            for key, value in new_metadata.items():
-                new_base_container.getMetaData()[key] = value
-        new_containers.append(new_base_container)
-
-        # Clone all of them.
-        for container_to_copy in container_registry.findContainers(base_file=root_material_id):
-            if container_to_copy.getId() == root_material_id:
-                continue  # We already have that one, skip it
-            new_id = new_base_id
-            if container_to_copy.getMetaDataEntry("definition") != "fdmprinter":
-                new_id += "_" + container_to_copy.getMetaDataEntry("definition")
-                if container_to_copy.getMetaDataEntry("variant_name"):
-                    nozzle_name = container_to_copy.getMetaDataEntry("variant_name")
-                    new_id += "_" + nozzle_name.replace(" ", "_")
-
-            new_container = copy.deepcopy(container_to_copy)
-            new_container.getMetaData()["id"] = new_id
-            new_container.getMetaData()["base_file"] = new_base_id
-            if new_metadata is not None:
-                for key, value in new_metadata.items():
-                    new_container.getMetaData()[key] = value
-            new_containers.append(new_container)
-
-        for container_to_add in new_containers:
-            container_to_add.setDirty(True)
-            container_registry.addContainer(container_to_add)
-
-        # if the duplicated material was favorite then the new material should also be added to favorite.
-        if root_material_id in self.getFavorites():
-            cura.CuraApplication.CuraApplication.getInstance().getMaterialManagementModel().addFavorite(new_base_id)
-
-        return new_base_id
-
-    #
-    # Creates a duplicate of a material, which has the same GUID and base_file metadata.
-    # Returns the root material ID of the duplicated material if successful.
-    #
-    @pyqtSlot("QVariant", result = str)
-    def duplicateMaterial(self, material_node: MaterialNode, new_base_id: Optional[str] = None,
-                          new_metadata: Optional[Dict[str, Any]] = None) -> str:
-        if material_node.container is None:
-            Logger.log("e", "Material node {0} doesn't have container.".format(material_node.container_id))
+    def duplicateMaterialByRootId(self, root_material_id: str, new_base_id: Optional[str] = None, new_metadata: Optional[Dict[str, Any]] = None) -> Optional[str]:
+        result = cura.CuraApplication.CuraApplication.getInstance().getMaterialManagementModel().duplicateMaterialByBaseFile(root_material_id, new_base_id, new_metadata)
+        if result is None:
             return "ERROR"
-        root_material_id = cast(str, material_node.container.getMetaDataEntry("base_file", ""))
-        new_material_id = self.duplicateMaterialByRootId(root_material_id, new_base_id, new_metadata)
-        return new_material_id if new_material_id is not None else "ERROR"
+        return result
 
-    # Create a new material by cloning Generic PLA for the current material diameter and generate a new GUID.
-    # Returns the ID of the newly created material.
+    ##  Creates a duplicate of a material with the same GUID and base_file
+    #   metadata.
+    #   \param material_node The node representing the material to duplicate.
+    #   \param new_base_id A new material ID for the base material. The IDs of
+    #   the submaterials will be based off this one. If not provided, a material
+    #   ID will be generated automatically.
+    #   \param new_metadata Metadata for the new material. If not provided, this
+    #   will be duplicated from the original material.
+    #   \return The root material ID of the duplicate material.
+    @pyqtSlot("QVariant", result = str)
+    def duplicateMaterial(self, material_node: MaterialNode, new_base_id: Optional[str] = None, new_metadata: Optional[Dict[str, Any]] = None) -> str:
+        result = cura.CuraApplication.CuraApplication.getInstance().getMaterialManagementModel().duplicateMaterial(material_node, new_base_id, new_metadata)
+        if result is None:
+            return "ERROR"
+        return result
+
+    ##  Create a new material by cloning the preferred material for the current
+    #   material diameter and generate a new GUID.
+    #
+    #   The material type is explicitly left to be the one from the preferred
+    #   material, since this allows the user to still have SOME profiles to work
+    #   with.
+    #   \return The ID of the newly created material.
     @pyqtSlot(result = str)
     def createMaterial(self) -> str:
-        from UM.i18n import i18nCatalog
-        catalog = i18nCatalog("cura")
-        # Ensure all settings are saved.
-        application = cura.CuraApplication.CuraApplication.getInstance()
-        application.saveSettings()
-
-        machine_manager = application.getMachineManager()
-        extruder_stack = machine_manager.activeStack
-
-        global_stack = application.getGlobalContainerStack()
-        if global_stack is None:
-            Logger.log("e", "Global stack not present!")
-            return "ERROR"
-        machine_definition = global_stack.definition
-        root_material_id = machine_definition.getMetaDataEntry("preferred_material", default = "generic_pla")
-
-        approximate_diameter = str(extruder_stack.approximateMaterialDiameter)
-        root_material_id = self.getRootMaterialIDForDiameter(root_material_id, approximate_diameter)
-
-        # Create a new ID & container to hold the data.
-        new_id = CuraContainerRegistry.getInstance().uniqueName("custom_material")
-        new_metadata = {"name": catalog.i18nc("@label", "Custom Material"),
-                        "brand": catalog.i18nc("@label", "Custom"),
-                        "GUID": str(uuid.uuid4()),
-                        }
-
-        self.duplicateMaterialByRootId(root_material_id, new_base_id = new_id, new_metadata = new_metadata)
-        return new_id
+        return cura.CuraApplication.CuraApplication.getMaterialManagementModel().createMaterial()
 
     @pyqtSlot(str)
     def addFavorite(self, root_material_id: str) -> None:
diff --git a/cura/Machines/Models/BaseMaterialsModel.py b/cura/Machines/Models/BaseMaterialsModel.py
index 66718e8e4f..e2c43ed883 100644
--- a/cura/Machines/Models/BaseMaterialsModel.py
+++ b/cura/Machines/Models/BaseMaterialsModel.py
@@ -127,8 +127,8 @@ class BaseMaterialsModel(ListModel):
             return
         nozzle_name = extruder_stack.variant.getName()
         materials = ContainerTree.getInstance().machines[global_stack.definition.getId()].variants[nozzle_name].materials
-        compatible_material_diameter = str(round(extruder_stack.getCompatibleMaterialDiameter()))
-        self._available_materials = {key: material for key, material in materials.items() if material.container.getMetaDataEntry("approximate_diameter") == compatible_material_diameter}
+        approximate_material_diameter = extruder_stack.getApproximateMaterialDiameter()
+        self._available_materials = {key: material for key, material in materials.items() if float(material.container.getMetaDataEntry("approximate_diameter")) == approximate_material_diameter}
 
     ## This method is used by all material models in the beginning of the
     #  _update() method in order to prevent errors. It's the same in all models
diff --git a/cura/Machines/Models/IntentCategoryModel.py b/cura/Machines/Models/IntentCategoryModel.py
index 5211889801..c436f94421 100644
--- a/cura/Machines/Models/IntentCategoryModel.py
+++ b/cura/Machines/Models/IntentCategoryModel.py
@@ -10,7 +10,7 @@ from cura.Settings.IntentManager import IntentManager
 from UM.Qt.ListModel import ListModel
 from UM.Settings.ContainerRegistry import ContainerRegistry #To update the list if anything changes.
 from PyQt5.QtCore import pyqtProperty, pyqtSignal
-
+import cura.CuraApplication
 if TYPE_CHECKING:
     from UM.Settings.ContainerRegistry import ContainerInterface
 
@@ -48,7 +48,7 @@ class IntentCategoryModel(ListModel):
 
         ContainerRegistry.getInstance().containerAdded.connect(self._onContainerChange)
         ContainerRegistry.getInstance().containerRemoved.connect(self._onContainerChange)
-        IntentManager.getInstance().configurationChanged.connect(self.update)
+        cura.CuraApplication.CuraApplication.getInstance().getMachineManager().activeStackChanged.connect(self.update)
 
         self.update()
 
diff --git a/cura/Machines/Models/IntentModel.py b/cura/Machines/Models/IntentModel.py
index 8773a12fd3..79d26db8d3 100644
--- a/cura/Machines/Models/IntentModel.py
+++ b/cura/Machines/Models/IntentModel.py
@@ -66,12 +66,26 @@ class IntentModel(ListModel):
 
         container_tree = ContainerTree.getInstance()
         machine_node = container_tree.machines[global_stack.definition.getId()]
-        active_extruder = ExtruderManager.getInstance().getActiveExtruderStack()
+
+        # We can't just look at the active extruder, since it is possible for only one extruder to have an intent
+        # and the other extruders have no intent (eg, default). It is not possible for one extruder to have intent A and
+        # the other to have B.
+        # So we will use the first extruder that we find that has an intent that is not default as the "active" extruder
+
+        active_extruder = None
+        for extruder in global_stack.extruderList:
+            if extruder.intent.getMetaDataEntry("intent_category", "default") == "default":
+                if active_extruder is None:
+                    active_extruder = extruder  # If there is no extruder found and the intent is default, use that.
+            else:  # We found an intent, use that extruder as "active"
+                active_extruder = extruder
+
         if not active_extruder:
             return
         active_variant_name = active_extruder.variant.getMetaDataEntry("name")
         active_variant_node = machine_node.variants[active_variant_name]
         active_material_node = active_variant_node.materials[active_extruder.material.getMetaDataEntry("base_file")]
+
         layer_heights_added = []
         for quality_id, quality_node in active_material_node.qualities.items():
             if quality_node.quality_type not in quality_groups:  # Don't add the empty quality type (or anything else that would crash, defensively).
diff --git a/cura/Machines/Models/MaterialManagementModel.py b/cura/Machines/Models/MaterialManagementModel.py
index f9af587293..a0b61e0b9b 100644
--- a/cura/Machines/Models/MaterialManagementModel.py
+++ b/cura/Machines/Models/MaterialManagementModel.py
@@ -73,20 +73,19 @@ class MaterialManagementModel(QObject):
 
     ##  Creates a duplicate of a material with the same GUID and base_file
     #   metadata.
-    #   \param material_node The node representing the material to duplicate.
+    #   \param base_file: The base file of the material to duplicate.
     #   \param new_base_id A new material ID for the base material. The IDs of
     #   the submaterials will be based off this one. If not provided, a material
     #   ID will be generated automatically.
     #   \param new_metadata Metadata for the new material. If not provided, this
     #   will be duplicated from the original material.
     #   \return The root material ID of the duplicate material.
-    @pyqtSlot("QVariant", result = str)
-    def duplicateMaterial(self, material_node: "MaterialNode", new_base_id: Optional[str] = None, new_metadata: Dict[str, Any] = None) -> Optional[str]:
+    def duplicateMaterialByBaseFile(self, base_file: str, new_base_id: Optional[str] = None, new_metadata: Dict[str, Any] = None) -> Optional[str]:
         container_registry = CuraContainerRegistry.getInstance()
 
-        root_materials = container_registry.findContainers(id = material_node.base_file)
+        root_materials = container_registry.findContainers(id = base_file)
         if not root_materials:
-            Logger.log("i", "Unable to duplicate the root material with ID {root_id}, because it doesn't exist.".format(root_id = material_node.base_file))
+            Logger.log("i", "Unable to duplicate the root material with ID {root_id}, because it doesn't exist.".format(root_id = base_file))
             return None
         root_material = root_materials[0]
 
@@ -105,8 +104,8 @@ class MaterialManagementModel(QObject):
         new_containers = [new_root_material]
 
         # Clone all submaterials.
-        for container_to_copy in container_registry.findInstanceContainers(base_file = material_node.base_file):
-            if container_to_copy.getId() == material_node.base_file:
+        for container_to_copy in container_registry.findInstanceContainers(base_file = base_file):
+            if container_to_copy.getId() == base_file:
                 continue  # We already have that one. Skip it.
             new_id = new_base_id
             definition = container_to_copy.getMetaDataEntry("definition")
@@ -129,12 +128,25 @@ class MaterialManagementModel(QObject):
 
         # If the duplicated material was favorite then the new material should also be added to the favorites.
         favorites_set = set(application.getPreferences().getValue("cura/favorite_materials").split(";"))
-        if material_node.base_file in favorites_set:
+        if base_file in favorites_set:
             favorites_set.add(new_base_id)
             application.getPreferences().setValue("cura/favorite_materials", ";".join(favorites_set))
 
         return new_base_id
 
+    ##  Creates a duplicate of a material with the same GUID and base_file
+    #   metadata.
+    #   \param material_node The node representing the material to duplicate.
+    #   \param new_base_id A new material ID for the base material. The IDs of
+    #   the submaterials will be based off this one. If not provided, a material
+    #   ID will be generated automatically.
+    #   \param new_metadata Metadata for the new material. If not provided, this
+    #   will be duplicated from the original material.
+    #   \return The root material ID of the duplicate material.
+    @pyqtSlot("QVariant", result = str)
+    def duplicateMaterial(self, material_node: "MaterialNode", new_base_id: Optional[str] = None, new_metadata: Dict[str, Any] = None) -> Optional[str]:
+        return self.duplicateMaterialByBaseFile(material_node.base_file, new_base_id, new_metadata)
+
     ##  Create a new material by cloning the preferred material for the current
     #   material diameter and generate a new GUID.
     #
diff --git a/cura/Machines/Models/QualityProfilesDropDownMenuModel.py b/cura/Machines/Models/QualityProfilesDropDownMenuModel.py
index 2311e80689..8b3999275d 100644
--- a/cura/Machines/Models/QualityProfilesDropDownMenuModel.py
+++ b/cura/Machines/Models/QualityProfilesDropDownMenuModel.py
@@ -78,9 +78,7 @@ class QualityProfilesDropDownMenuModel(ListModel):
         quality_group_dict = ContainerTree.getInstance().getCurrentQualityGroups()
 
         item_list = []
-        for key in quality_group_dict:
-            quality_group = quality_group_dict[key]
-
+        for quality_group in quality_group_dict.values():
             layer_height = self._fetchLayerHeight(quality_group)
 
             item = {"name": quality_group.name,
diff --git a/cura/Machines/QualityManager.py b/cura/Machines/QualityManager.py
index 4a5a4c0885..6c54a6890d 100644
--- a/cura/Machines/QualityManager.py
+++ b/cura/Machines/QualityManager.py
@@ -5,7 +5,6 @@ from typing import Any, Dict, List, Optional, TYPE_CHECKING
 
 from PyQt5.QtCore import QObject, pyqtSignal, pyqtSlot
 
-from UM.Logger import Logger
 from UM.Util import parseBool
 from UM.Settings.InstanceContainer import InstanceContainer
 from UM.Decorators import deprecated
diff --git a/cura/Settings/IntentManager.py b/cura/Settings/IntentManager.py
index 251cf0aed8..1a73fb818c 100644
--- a/cura/Settings/IntentManager.py
+++ b/cura/Settings/IntentManager.py
@@ -4,6 +4,7 @@
 from PyQt5.QtCore import QObject, pyqtProperty, pyqtSignal, pyqtSlot
 from typing import Any, Dict, List, Optional, Set, Tuple, TYPE_CHECKING
 import cura.CuraApplication
+from UM.Logger import Logger
 from cura.Machines.ContainerTree import ContainerTree
 from cura.Settings.cura_empty_instance_containers import empty_intent_container
 from UM.Settings.InstanceContainer import InstanceContainer
@@ -11,20 +12,12 @@ from UM.Settings.InstanceContainer import InstanceContainer
 if TYPE_CHECKING:
     from UM.Settings.InstanceContainer import InstanceContainer
 
+
 ##  Front-end for querying which intents are available for a certain
 #   configuration.
-#
-#   CURRENTLY THIS CLASS CONTAINS ONLY SOME PSEUDOCODE OF WHAT WE ARE SUPPOSED
-#   TO IMPLEMENT.
 class IntentManager(QObject):
     __instance = None
 
-    def __init__(self) -> None:
-        super().__init__()
-        cura.CuraApplication.CuraApplication.getInstance().getMachineManager().activeStackChanged.connect(self.configurationChanged)
-        self.configurationChanged.connect(self.selectDefaultIntent)
-        pass
-
     ##  This class is a singleton.
     @classmethod
     def getInstance(cls):
@@ -32,7 +25,6 @@ class IntentManager(QObject):
             cls.__instance = IntentManager()
         return cls.__instance
 
-    configurationChanged = pyqtSignal() #Triggered when something changed in the rest of the stack.
     intentCategoryChanged = pyqtSignal() #Triggered when we switch categories.
 
     ##  Gets the metadata dictionaries of all intent profiles for a given
@@ -40,12 +32,16 @@ class IntentManager(QObject):
     #
     #   \param definition_id ID of the printer.
     #   \param nozzle_name Name of the nozzle.
-    #   \param material_id ID of the material.
+    #   \param material_base_file The base_file of the material.
     #   \return A list of metadata dictionaries matching the search criteria, or
     #   an empty list if nothing was found.
-    def intentMetadatas(self, definition_id: str, nozzle_name: str, material_id: str) -> List[Dict[str, Any]]:
-        registry = cura.CuraApplication.CuraApplication.getInstance().getContainerRegistry()
-        return registry.findContainersMetadata(type = "intent", definition = definition_id, variant = nozzle_name, material = material_id)
+    def intentMetadatas(self, definition_id: str, nozzle_name: str, material_base_file: str) -> List[Dict[str, Any]]:
+        material_node = ContainerTree.getInstance().machines[definition_id].variants[nozzle_name].materials[material_base_file]
+        intent_metadatas = []
+        for quality_node in material_node.qualities.values():
+            for intent_node in quality_node.intents.values():
+                intent_metadatas.append(intent_node.getMetadata())
+        return intent_metadatas
 
     ##  Collects and returns all intent categories available for the given
     #   parameters. Note that the 'default' category is always available.
@@ -77,7 +73,6 @@ class IntentManager(QObject):
             #       even though there should always be defaults. The problem then is what to do with the quality_types.
             #       Currently _also_ inconsistent with 'currentAvailableIntentCategories', which _does_ return default.
         quality_groups = ContainerTree.getInstance().getCurrentQualityGroups()
-        # TODO: These quality nodes in that tree already contain the intent nodes. We can optimise this.
         available_quality_types = {quality_group.quality_type for quality_group in quality_groups.values() if quality_group.node_for_global is not None}
 
         final_intent_ids = set()  # type: Set[str]
@@ -131,6 +126,7 @@ class IntentManager(QObject):
     ##  Apply intent on the stacks.
     @pyqtSlot(str, str)
     def selectIntent(self, intent_category: str, quality_type: str) -> None:
+        Logger.log("i", "Attempting to set intent_category to [%s] and quality type to [%s]", intent_category, quality_type)
         old_intent_category = self.currentIntentCategory
         application = cura.CuraApplication.CuraApplication.getInstance()
         global_stack = application.getGlobalContainerStack()
@@ -147,13 +143,4 @@ class IntentManager(QObject):
                 extruder_stack.intent = self.getDefaultIntent()
         application.getMachineManager().setQualityGroupByQualityType(quality_type)
         if old_intent_category != intent_category:
-            self.intentCategoryChanged.emit()
-
-    ##  Selects the default intents on every extruder.
-    def selectDefaultIntent(self) -> None:
-        application = cura.CuraApplication.CuraApplication.getInstance()
-        global_stack = application.getGlobalContainerStack()
-        if global_stack is None:
-            return
-        for extruder_stack in global_stack.extruderList:
-            extruder_stack.intent = self.getDefaultIntent()
+            self.intentCategoryChanged.emit()
\ No newline at end of file
diff --git a/cura/Settings/MachineManager.py b/cura/Settings/MachineManager.py
index a8d7379cf7..4ff5ad95cd 100755
--- a/cura/Settings/MachineManager.py
+++ b/cura/Settings/MachineManager.py
@@ -26,7 +26,6 @@ import cura.CuraApplication  # Imported like this to prevent circular references
 
 from cura.Machines.ContainerNode import ContainerNode
 from cura.Machines.ContainerTree import ContainerTree
-from cura.Machines.MaterialManager import MaterialManager
 
 from cura.PrinterOutput.PrinterOutputDevice import PrinterOutputDevice, ConnectionType
 from cura.PrinterOutput.Models.PrinterConfigurationModel import PrinterConfigurationModel
@@ -616,10 +615,15 @@ class MachineManager(QObject):
 
     @pyqtProperty(str, notify=activeIntentChanged)
     def activeIntentCategory(self):
+        global_container_stack = cura.CuraApplication.CuraApplication.getInstance().getGlobalContainerStack()
 
-        if not self._active_container_stack:
+        if not global_container_stack:
             return ""
-        intent_category = self._active_container_stack.intent.getMetaDataEntry("intent_category")
+        intent_category = "default"
+        for extruder in global_container_stack.extruderList:
+            category = extruder.intent.getMetaDataEntry("intent_category", "default")
+            if category != "default" and category != intent_category:
+                intent_category = category
         return intent_category
 
     ##  Returns whether there is anything unsupported in the current set-up.
@@ -1301,8 +1305,7 @@ class MachineManager(QObject):
                 self._setMaterial(position_item, new_material)
             else:
                 # The current material is not available, find the preferred one.
-                material_diameter = self._global_container_stack.extruders[position].getCompatibleMaterialDiameter()
-                approximate_material_diameter = round(material_diameter)
+                approximate_material_diameter = int(self._global_container_stack.extruderList[int(position)].getApproximateMaterialDiameter())
                 material_node = nozzle_node.preferredMaterial(approximate_material_diameter)
                 self._setMaterial(position_item, material_node)
 
@@ -1343,6 +1346,7 @@ class MachineManager(QObject):
         if self._global_container_stack is None:
             return
         self.blurSettings.emit()
+        container_registry = CuraContainerRegistry.getInstance()
         with postponeSignals(*self._getContainerChangedSignals(), compress = CompressTechnique.CompressPerParameterValue):
             self.switchPrinterType(configuration.printerType)
 
@@ -1379,20 +1383,18 @@ class MachineManager(QObject):
                 else:
                     machine_node = ContainerTree.getInstance().machines.get(self._global_container_stack.definition.getId())
                     variant_node = machine_node.variants.get(extruder_configuration.hotendID)
-                    if variant_node:
-                        self._setVariantNode(position, variant_node)
-                    else:
-                        self._global_container_stack.extruders[position].variant = empty_variant_container
+                    self._setVariantNode(position, variant_node)
 
-                    material_container_node = MaterialManager.getInstance().getMaterialNodeByType(self._global_container_stack,
-                                                                                           position,
-                                                                                           extruder_configuration.hotendID,
-                                                                                           configuration.buildplateConfiguration,
-                                                                                           extruder_configuration.material.guid)
-                    if material_container_node:
-                        self._setMaterial(position, material_container_node)
-                    else:
-                        self._global_container_stack.extruders[position].material = empty_material_container
+                    # Find the material profile that the printer has stored.
+                    # This might find one of the duplicates if the user duplicated the material to sync with. But that's okay; both have this GUID so both are correct.
+                    approximate_diameter = int(self._global_container_stack.extruderList[int(position)].getApproximateMaterialDiameter())
+                    materials_with_guid = container_registry.findInstanceContainersMetadata(guid = extruder_configuration.material.guid, approximate_diameter = approximate_diameter)
+                    material_container_node = variant_node.preferredMaterial(approximate_diameter)
+                    if materials_with_guid:  # We also have the material profile that the printer wants to share.
+                        base_file = materials_with_guid[0]["base_file"]
+                        material_container_node = variant_node.materials.get(base_file, default = material_container_node)  # If Cura thinks that the selected material is not available for this printer, revert to the preferred material.
+
+                    self._setMaterial(position, material_container_node)
                     self._global_container_stack.extruders[position].setEnabled(True)
                     self.updateMaterialWithVariant(position)
 
@@ -1431,17 +1433,12 @@ class MachineManager(QObject):
     def setMaterialById(self, position: str, root_material_id: str) -> None:
         if self._global_container_stack is None:
             return
-        buildplate_name = None
-        if self._global_container_stack.variant.getId() != "empty_variant":
-            buildplate_name = self._global_container_stack.variant.getName()
 
         machine_definition_id = self._global_container_stack.definition.id
         position = str(position)
         extruder_stack = self._global_container_stack.extruders[position]
         nozzle_name = extruder_stack.variant.getName()
-        material_diameter = extruder_stack.getApproximateMaterialDiameter()
-        material_node = MaterialManager.getInstance().getMaterialNode(machine_definition_id, nozzle_name, buildplate_name,
-                                                               material_diameter, root_material_id)
+        material_node = ContainerTree.getInstance().machines[machine_definition_id].variants[nozzle_name].materials[root_material_id]
         self.setMaterial(position, material_node)
 
     ##  Global_stack: if you want to provide your own global_stack instead of the current active one
@@ -1624,7 +1621,3 @@ class MachineManager(QObject):
                 abbr_machine += stripped_word
 
         return abbr_machine
-
-    # Gets all machines that belong to the given group_id.
-    def getMachinesInGroup(self, group_id: str) -> List["GlobalStack"]:
-        return self._container_registry.findContainerStacks(type = "machine", group_id = group_id)
diff --git a/plugins/MachineSettingsAction/MachineSettingsAction.py b/plugins/MachineSettingsAction/MachineSettingsAction.py
index d48475b1e6..25586ddeb0 100755
--- a/plugins/MachineSettingsAction/MachineSettingsAction.py
+++ b/plugins/MachineSettingsAction/MachineSettingsAction.py
@@ -11,7 +11,9 @@ from UM.Settings.ContainerRegistry import ContainerRegistry
 from UM.Settings.DefinitionContainer import DefinitionContainer
 from UM.Util import parseBool
 
+import cura.CuraApplication  # Imported like this to prevent circular dependencies.
 from cura.MachineAction import MachineAction
+from cura.Machines.ContainerTree import ContainerTree  # To re-build the machine node when hasMaterials changes.
 from cura.Settings.CuraStackBuilder import CuraStackBuilder
 from cura.Settings.cura_empty_instance_containers import isEmptyContainer
 
@@ -41,6 +43,9 @@ class MachineSettingsAction(MachineAction):
         self._backend = self._application.getBackend()
         self.onFinished.connect(self._onFinished)
 
+        # If the g-code flavour changes between UltiGCode and another flavour, we need to update the container tree.
+        self._application.globalContainerStackChanged.connect(self._updateHasMaterialsInContainerTree)
+
     # Which container index in a stack to store machine setting changes.
     @pyqtProperty(int, constant = True)
     def storeContainerIndex(self) -> int:
@@ -51,6 +56,16 @@ class MachineSettingsAction(MachineAction):
         if isinstance(container, DefinitionContainer) and container.getMetaDataEntry("type") == "machine":
             self._application.getMachineActionManager().addSupportedAction(container.getId(), self.getKey())
 
+    ##  Triggered when the global container stack changes or when the g-code
+    #   flavour setting is changed.
+    def _updateHasMaterialsInContainerTree(self) -> None:
+        global_stack = cura.CuraApplication.CuraApplication.getInstance().getGlobalContainerStack()
+        machine_node = ContainerTree.getInstance().machines[global_stack.definition.getId()]
+
+        if machine_node.has_materials != parseBool(global_stack.getMetaDataEntry("has_materials")):  # May have changed due to the g-code flavour.
+            machine_node.has_materials = parseBool(global_stack.getMetaDataEntry("has_materials"))
+            machine_node._loadAll()
+
     def _reset(self):
         global_stack = self._application.getMachineManager().activeMachine
         if not global_stack:
@@ -98,11 +113,8 @@ class MachineSettingsAction(MachineAction):
             return
 
         machine_manager = self._application.getMachineManager()
-        material_manager = self._application.getMaterialManager()
-        extruder_positions = list(global_stack.extruders.keys())
         has_materials = global_stack.getProperty("machine_gcode_flavor", "value") != "UltiGCode"
 
-        material_node = None
         if has_materials:
             global_stack.setMetaDataEntry("has_materials", True)
         else:
@@ -111,11 +123,15 @@ class MachineSettingsAction(MachineAction):
             if "has_materials" in global_stack.getMetaData():
                 global_stack.removeMetaDataEntry("has_materials")
 
+        self._updateHasMaterialsInContainerTree()
+
         # set materials
-        for position in extruder_positions:
-            if has_materials:
-                material_node = material_manager.getDefaultMaterial(global_stack, position, None)
-            machine_manager.setMaterial(position, material_node)
+        machine_node = ContainerTree.getInstance().machines[global_stack.definition.getId()]
+        for position, extruder in enumerate(global_stack.extruderList):
+            #Find out what material we need to default to.
+            approximate_diameter = round(extruder.getProperty("material_diameter", "value"))
+            material_node = machine_node.variants[extruder.variant.getName()].preferredMaterial(approximate_diameter)
+            machine_manager.setMaterial(str(position), material_node)
 
         self._application.globalContainerStackChanged.emit()
 
diff --git a/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py b/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
index 5637f388c1..09949ed37e 100644
--- a/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
+++ b/plugins/UM3NetworkPrinting/src/Network/SendMaterialJob.py
@@ -69,9 +69,9 @@ class SendMaterialJob(Job):
     def _sendMaterials(self, materials_to_send: Set[str]) -> None:
         container_registry = CuraApplication.getInstance().getContainerRegistry()
         all_materials = container_registry.findInstanceContainersMetadata(type = "material")
-        all_root_materials = {material["base_file"] for material in all_materials if "base_file" in material}  # Filters out uniques by making it a set. Don't include files without base file (i.e. empty material).
+        all_base_files = {material["base_file"] for material in all_materials if "base_file" in material}  # Filters out uniques by making it a set. Don't include files without base file (i.e. empty material).
 
-        for root_material_id in all_root_materials:
+        for root_material_id in all_base_files:
             if root_material_id not in materials_to_send:
                 # If the material does not have to be sent we skip it.
                 continue
@@ -129,10 +129,10 @@ class SendMaterialJob(Job):
     def _getLocalMaterials() -> Dict[str, LocalMaterial]:
         result = {}  # type: Dict[str, LocalMaterial]
         all_materials = CuraApplication.getInstance().getContainerRegistry().findInstanceContainersMetadata(type = "material")
-        all_root_materials = [material for material in all_materials if material["id"] == material.get("base_file")]  # Don't send materials without base_file: The empty material doesn't need to be sent.
+        all_base_files = [material for material in all_materials if material["id"] == material.get("base_file")]  # Don't send materials without base_file: The empty material doesn't need to be sent.
 
         # Find the latest version of all material containers in the registry.
-        for material_metadata in all_root_materials:
+        for material_metadata in all_base_files:
             try:
                 # material version must be an int
                 material_metadata["version"] = int(material_metadata["version"])
diff --git a/resources/qml/PrintSetupSelector/Custom/MenuButton.qml b/resources/qml/PrintSetupSelector/Custom/MenuButton.qml
index 29436da9cf..cebe130a20 100644
--- a/resources/qml/PrintSetupSelector/Custom/MenuButton.qml
+++ b/resources/qml/PrintSetupSelector/Custom/MenuButton.qml
@@ -22,7 +22,7 @@ Button
     background: Rectangle
     {
         id: backgroundRectangle
-        border.width: 1
+        border.width: UM.Theme.getSize("default_lining").width
         border.color: button.checked ? UM.Theme.getColor("setting_control_border_highlight") : "transparent"
         color: button.hovered ? UM.Theme.getColor("action_button_hovered") : "transparent"
         radius: UM.Theme.getSize("action_button_radius").width
diff --git a/resources/qml/PrintSetupSelector/Custom/QualitiesWithIntentMenu.qml b/resources/qml/PrintSetupSelector/Custom/QualitiesWithIntentMenu.qml
index 94f9acf3b3..cff4e3e7a6 100644
--- a/resources/qml/PrintSetupSelector/Custom/QualitiesWithIntentMenu.qml
+++ b/resources/qml/PrintSetupSelector/Custom/QualitiesWithIntentMenu.qml
@@ -182,11 +182,12 @@ Popup
 
         Rectangle
         {
-            height: 1
+            height: UM.Theme.getSize("default_lining").height
             anchors.left: parent.left
             anchors.right: parent.right
             color: borderColor
         }
+
         MenuButton
         {
             labelText: Cura.Actions.addProfile.text
diff --git a/resources/qml/RadioCheckbar.qml b/resources/qml/RadioCheckbar.qml
index 3c767a6201..59dba59910 100644
--- a/resources/qml/RadioCheckbar.qml
+++ b/resources/qml/RadioCheckbar.qml
@@ -14,7 +14,7 @@ Item
     property color activeColor: UM.Theme.getColor("primary")
     property color inactiveColor: UM.Theme.getColor("slider_groove")
     property color defaultItemColor: UM.Theme.getColor("small_button_active")
-    property int checkboxSize: UM.Theme.getSize("radio_button").height * 0.75
+    property int checkboxSize: Math.round(UM.Theme.getSize("radio_button").height * 0.75)
     property int inactiveMarkerSize: 2 * barSize
     property int barSize: UM.Theme.getSize("slider_groove_radius").height
     property var isCheckedFunction // Function that accepts the modelItem and returns if the item should be active.
@@ -36,8 +36,8 @@ Item
         {
             left: buttonBar.left
             right: buttonBar.right
-            leftMargin: (checkboxSize - inactiveMarkerSize) / 2
-            rightMargin: (checkboxSize - inactiveMarkerSize) / 2
+            leftMargin: Math.round((checkboxSize - inactiveMarkerSize) / 2)
+            rightMargin: Math.round((checkboxSize - inactiveMarkerSize) / 2)
             verticalCenter: parent.verticalCenter
         }
     }
@@ -72,7 +72,7 @@ Item
                     property Item previousItem: repeater.itemAt(index - 1)
 
                     height: barSize
-                    width: buttonBar.width / (repeater.count - 1) - activeComponent.width - 2
+                    width: Math.round(buttonBar.width / (repeater.count - 1) - activeComponent.width - 2)
                     color: defaultItemColor
 
                     anchors
@@ -110,7 +110,7 @@ Item
                 anchors.horizontalCenter: parent.horizontalCenter
                 height: inactiveMarkerSize
                 width: inactiveMarkerSize
-                radius: width / 2
+                radius: Math.round(width / 2)
                 color: inactiveColor
             }
         }
@@ -132,7 +132,7 @@ Item
             {
                 height: checkboxSize
                 width: checkboxSize
-                radius: width / 2
+                radius: Math.round(width / 2)
 
                 border.color: defaultItemColor
 
@@ -143,7 +143,7 @@ Item
                         margins: 3
                         fill: parent
                     }
-                    radius: width / 2
+                    radius: Math.round(width / 2)
                     color: activeColor
                     visible: checkbox.checked
                 }