I've a stress injury to my thumb (workout gone wrong) and I was in need of a brace but din't like the commercial ones...specially because I often go to swim or paddle in open waters. So I though to make one, I've 3d scanned my hand and worked on the 3d model in order to smooth and apply a voronoi pattern.

The idea was a closed brace to fit like a glove using TPU elastic filament.

I've tried it and wearing it right now (see photo) but I can tell you is not the right way to do a brace for the thumbs.

The problem is that TPU cannot expand enough to wear the brace easily. I can barely fit the fingers and obviously if you have an injury you can't force so much.

Keep in mind that is suited for my hand size. Right printing scale for me were measuring the wrist width (52mm) and scale the internal wrist hole in the model adding about 5mm more (so 57mm width at the wrist)

Anyway is a nice start point and I plan to work more on it if I've time