Object scale

I have a project with a cow and I want to make an app so I can scale parts of the cow!
The cow was made in Blender!
Can you give me a little idea of how can I make a script or what should I do to scale parts of the cow, without affecting the unit of the cow…I mean just to resize parts of it?
I don’t want a lot of details…I just want some advices so I can continue my work.
It’s enough to know just how can I rescale parts of cow…then I will figure it out how to make the scale script.
I thought about pivots…but I don’t know.
Thanks in advance! :smiley:

You can rig it with bones so that you can scale part of the 3d model by scaling the bone. If you want a more detailed control, then you probably need to write a script to modify the mesh