figuring out the arm attachment. its inspired from the youtube video, but mine will be all 3d prints so i can skip out and simplify a little. the idea is two brackets with a hex shaft between them and bearings. one end has a magnetic encoder to detect hex shaft rotation, and the other end will attach to a 3d print with a hex slot that will rotate. then, in the joint between arms, it will be a bearing and encoder on one end, and another 3d print with a hex slot on the other end.