How do you make an elbow hinge joint that shows how muscles work?
You could use two pieces of wood, like 2x3x8 and 2x3x12. Attach them with a small hinge so the end of the 12″ piece is about 1″ from the end of the 8″ piece. Then attach rubber bands from the other end of the 12″ piece. Attach the other end of one rubber band at the short end of the 8″ piece that would then be the triceps attaching to your elbow. And attach the other rubber band about 2″ past the hinge on the 8″ piece as the biceps. Look at your own arms and illustrations to visualize how to make the attachments.
