I started printing out one part of a larger system I'll be using for my thesis. It consists of an inner plate and an outer ring that can be spun independently by two stepper motors. I printed a few of the parts, then before printing the final large base *I made some test prints to check everything would fit*. If you haven't thought of doing this yet, it can save so much time. In this case, the most important test was what diameter should the center raised rod be to mate with the 15mm hole in the middle of the inner plate. 14.8 was a little too snug but could easily have been sanded down. 14.6mm was perfect, so I stopped testing and printed the main part. Here;s the full assembly:

To attach the gears to my salvaged steppers, I heated up the gears that were already on the steppers (from an old printer) and pushed the hot metal into a slightly undersized hole. Seems to have worked well. Lesson for next time: bevel the hole to help keep things centered:

I'll update on this project at a later date.