The upper base was contoured based on the KUKA KR-10 robot, as I found it visually appealing. On the outside, it features an encoder, and on the inside, there is a sun gear bolted to the face on which two planet gears from the first axis motors will drive around. This part was also printed from a 0.6mm nozzle, and in the middle, there was a slight hiccup but I solved that with some simple filler and acrylic cement, The encoder wires go into the main hole through small holes, and beneath the upper base piece is a hex axle which goes into a hole and sticks down through the bearing at the bottom of the lower base piece. On this axle is a gear, which the base motor drives using a motor hosted on the inside.