As my daughter grew, the existing design just didn't scale as well as I would have liked.  Also, I had printed all of the original pieces on a first generation Printrbot.  It was an awesome piece of equipment at the time, but 3D printers have come a long way since then.  Last Christmas, I decided I'd update the design and give my daughter new arm floats.  And, to get the job done, I decided I really "needed" a new Prusa Mk3s.  Wow, what a difference that printer makes!  I was able to dial in the tolerances on the parts quite a bit.

The updated design is overall stronger and lighter.  There's less slack in the joints.  The angle is easily adjustable (great for wheelchairs that tilt in space).  

For anyone interested in making one, feel free to reach out to me-- I love to hear about builds and would be happy to help out with any snags.

https://www.prusaprinters.org/prints/22203-antigravity-arm-floats-v2