thingiverse user Dvogonen shares:

I recently had troubles with a painful muscular inflammation. Using a massage roller did help, but the roller I had was tiresome and clumsy to use. It had a uncomfortable handle that made my fingers cramp up. What I wanted was a massage roller that would fit in the palm of my hand and would not require any grip strength. The result is the device in the pictures. I am quite happy with the result.