To be clear, this is not a piece of medical equipment and I am not a doctor, or acupuncturist, or any kind of pokey-thing authority. So, if you get a booboo, don't come after me. This thing hurts and makes my handwriting illegible, but with persistence, it gets easier with time and has helped to regain some strength and ROM after an accident a few years ago. It's a literal pain to assemble at first, so I wrapped it in a cloth and smashed the eraser end on some cement to get the pencil through. Gets easier as it wears down, though. Slapped it together pretty quickly, so its not symmetrical or pretty.
The author remixed this model.
Added a whole bunch of little stabby bits.