I cut the top plate yesterday, all I need now is a way to build a joystick shaft, ideally with a smooth half-sphere pivot. The best idea I had so far was using a drilled nylon acorn nut, resting on the edge of the round hole of the top PVC plate. I'm not sure what the durability of the nylon will do to the PVC plate, worst case scenario I'm guessing I'll have to cut the top plate again to allow the insertion of a nylon washer to make contact with the nylon acorn nut.
Other than that, a joystick is just a shaft with a spring. I'll be using a ball top since it's going to be easier to find a small round ball than a tiny bat top. And I also need to find eight tiny bolts to secure the switches together with the two plates.