The below example is arbitrary since I cannot post files. I have a custom assembly (wall) that has multiple custom extrusions (stud). The length of the "stud" is tied to the "wall" assy height. The "wall" assembly is then added to another assembly (house) that uses many "wall" assemblies that contain many "stud" parts. In the end there are many "studs" that have many different lengths.The CAD operator