This is the back support when you're doing donkey raise calf excercise. You have to place thr rod of weight bar. You can attache and detache quickly from the rod. The main unit has foam support to make comfort. Manufacturable STEP file format attached. I put it in 3d printing category because of I attached manufacturable STEP file format. It's suitable for injection molding.

If you want custom design and size please contact with me.

Thanks,Mahbub