“If you want to build a ship, don't drum up people together to collect wood and don't assign them tasks and work, but rather teach them to long for the endless immensity of the sea” Antoine de Saint-Exupery
I spent about two hours putting together this mock-up of an arm for a boxing robot. I built it to figure out the geometry required to get the motion I was after, while keeping with one degree of freedom. It's built with a standard hobby servo and my arduino running the servo library. the forearm is 6.5 inches, and it's on scale for a 45 inch tall robot.
