How it's made. The ball is 12 mm (or 18 mm for the big kit) on a 6 mm stem; the socket's cup is 0.4 mm over the ball with a mouth 1.2 mm under it, so it snaps over and grips - four 0.8 mm slits let the cup flex, and the wall is 2.4 mm so it lasts. The rod carries a socket at each end, the T three, the plate four; the figure's torso plate takes the neck, both shoulders and both hips, and each limb is a rod with a ball at one end and a socket at the other, so it bends at every joint and holds. Every part prints flat, no supports; PLA or PETG for a joint that stays springy.