diff --git a/docs/demo/scripts/customise_interactions.py b/docs/demo/scripts/customise_interactions.py
index bc86bba8..02e70e44 100644
--- a/docs/demo/scripts/customise_interactions.py
+++ b/docs/demo/scripts/customise_interactions.py
@@ -338,31 +338,11 @@ def custom_handler_function(x):
 
 
 # %%
-def wrap(func):
-    """
-
-    Args:
-        func:
-
-    Returns:
-
-    """
-
-    def pull_distributed_wrapper(x):
-        """
-
-        Args:
-            x:
-
-        Returns:
-
-        """
-        return func(x, tag="FWTW")
-
-    return pull_distributed_wrapper
-
-
-my_fwtw.pull_distributed = wrap(my_fwtw.pull_distributed)
+from wsimod.extensions import extensions as extend
+@extend.model_attribute(obj=my_fwtw, attribute_name="pull_distributed")
+def new_distributed(pull_distributed, vqip):
+     """pull_distributed with the tag 'FWTW'."""
+     return pull_distributed(vqip, tag="FWTW")
 
 # %% [markdown]
 # Explaining decorators is outside the scope of this tutorial, though you can
diff --git a/wsimod/extensions/extensions.py b/wsimod/extensions/extensions.py
new file mode 100644
index 00000000..31a1b2e8
--- /dev/null
+++ b/wsimod/extensions/extensions.py
@@ -0,0 +1,33 @@
+def model_attribute(obj, attribute_name):
+    """
+    Decorator to extend or modify a model attribute.
+
+    Args:
+        obj: The model object whose attribute should be modified.
+        attribute_name (str): The name of the attribute to modify.
+
+    Returns:
+        A decorator function that takes the extension function as an argument.
+    """
+    def decorator(func):
+        """
+        Decorator function that applies the extension function to the model attribute.
+
+        Args:
+            func: The extension function that modifies the model attribute.
+        """
+        attribute = getattr(obj, attribute_name)
+        
+        def wrapped_attribute(*args, **kwargs):
+            return func(attribute, *args, **kwargs)
+
+        setattr(obj, attribute_name, wrapped_attribute)
+        return wrapped_attribute
+
+    return decorator
+
+    
+@model_attribute(obj=my_fwtw, attribute_name="pull_distributed")
+def new_distributed(pull_distributed, vqip):
+     """pull_distributed with the tag 'FWTW'."""
+     return pull_distributed(vqip, tag="FWTW")
\ No newline at end of file