diff --git a/__init__.py b/__init__.py
index af254e8..d30e15e 100644
--- a/__init__.py
+++ b/__init__.py
@@ -780,6 +780,21 @@ class SLICENODE_GcodeToMesh(ExecSliceNode):
         mesh.from_pydata(vertices, edges, [])
         mesh.update()
 
+        # Assign Geometry Nodes nodegroup for preview
+        ng_name = "Nonplanar Slicing Preview"
+        if ng_name in bpy.data.node_groups:
+            ng = bpy.data.node_groups[ng_name]
+            # Check if already assigned
+            has_preview = False
+            for mod in obj.modifiers:
+                if mod.type == 'NODES' and mod.node_group == ng: # type: ignore
+                    has_preview = True
+                    break
+            
+            if not has_preview:
+                mod = obj.modifiers.new(name="Preview", type='NODES') # type: ignore
+                mod.node_group = ng
+
         return 'ok'
 
 @register_class