diff --git a/InvenTree/part/models.py b/InvenTree/part/models.py
index 2489c453ad..b9d7e71c86 100644
--- a/InvenTree/part/models.py
+++ b/InvenTree/part/models.py
@@ -96,7 +96,7 @@ class PartParameterTemplate(models.Model):
     ready to be copied for use with a given Part.
     A PartParameterTemplate can be optionally associated with a PartCategory
     """
-    name = models.CharField(max_length=20)
+    name = models.CharField(max_length=20, unique=True)
     units = models.CharField(max_length=10, blank=True)
 
     # Parameter format
@@ -138,32 +138,13 @@ class CategoryParameterLink(models.Model):
     class Meta:
         verbose_name = "Category Parameter"
         verbose_name_plural = "Category Parameters"
-
-
-class PartParameterManager(models.Manager):
-    """ Manager for handling PartParameter objects
-    """
-
-    def create(self, *args, **kwargs):
-        """ Prevent creation of duplicate PartParameter
-        """
-
-        part_id = kwargs['part']
-        template_id = kwargs['template']
-
-        params = self.filter(part=part_id, template=template_id)
-        if len(params) > 0:
-            return params[0]
-
-        return super(PartParameterManager, self).create(*args, **kwargs)
+        unique_together = ('category', 'template')
 
 
 class PartParameter(models.Model):
     """ PartParameter is associated with a single part
     """
 
-    objects = PartParameterManager()
-
     part = models.ForeignKey(Part, on_delete=models.CASCADE, related_name='parameters')
     template = models.ForeignKey(PartParameterTemplate)
 
diff --git a/InvenTree/project/models.py b/InvenTree/project/models.py
index 6cc8a01ce0..8038184215 100644
--- a/InvenTree/project/models.py
+++ b/InvenTree/project/models.py
@@ -31,44 +31,26 @@ class Project(models.Model):
     description = models.CharField(max_length=500, blank=True)
     category = models.ForeignKey(ProjectCategory, on_delete=models.CASCADE, related_name='projects')
 
+    class Meta:
+        unique_together = ('name', 'category')
+
     def __str__(self):
         return self.name
 
 
-class ProjectPartManager(models.Manager):
-    """ Manager for handling ProjectParts
-    """
-
-    def create(self, *args, **kwargs):
-        """ Test for validity of new ProjectPart before actually creating it.
-        If a ProjectPart already exists that references the same:
-        a) Part
-        b) Project
-        then return THAT project instead.
-        """
-
-        project_id = kwargs['project']
-        part_id = kwargs['part']
-
-        project_parts = self.filter(project=project_id, part=part_id)
-        if len(project_parts) > 0:
-            return project_parts[0]
-
-        return super(ProjectPartManager, self).create(*args, **kwargs)
-
-
 class ProjectPart(models.Model):
     """ A project part associates a single part with a project
     The quantity of parts required for a single-run of that project is stored.
     The overage is the number of extra parts that are generally used for a single run.
     """
 
-    objects = ProjectPartManager()
-
     part = models.ForeignKey(Part, on_delete=models.CASCADE)
     project = models.ForeignKey(Project, on_delete=models.CASCADE)
     quantity = models.PositiveIntegerField(default=1)
 
+    class Meta:
+        unique_together = ('part', 'project')
+
     """
     # TODO - Add overage model fields
 
diff --git a/InvenTree/stock/models.py b/InvenTree/stock/models.py
index dc5f412420..b7f3932c12 100644
--- a/InvenTree/stock/models.py
+++ b/InvenTree/stock/models.py
@@ -17,9 +17,7 @@ class StockLocation(InvenTreeTree):
 
 
 class StockItem(models.Model):
-    part = models.ForeignKey(Part,
-                             on_delete=models.CASCADE,
-                             related_name='locations')
+    part = models.ForeignKey(Part, on_delete=models.CASCADE, related_name='locations')
     location = models.ForeignKey(StockLocation, on_delete=models.CASCADE)
     quantity = models.PositiveIntegerField()
     updated = models.DateField(auto_now=True)
diff --git a/InvenTree/supplier/models.py b/InvenTree/supplier/models.py
index 894621ea97..9f5067caf8 100644
--- a/InvenTree/supplier/models.py
+++ b/InvenTree/supplier/models.py
@@ -78,6 +78,9 @@ class SupplierPriceBreak(models.Model):
     quantity = models.PositiveIntegerField()
     cost = models.DecimalField(max_digits=10, decimal_places=3)
 
+    class Meta:
+        unique_together = ("part", "quantity")
+
     def __str__(self):
         return "{mpn} - {cost}{currency} @ {quan}".format(
             mpn=self.part.MPN,