I spent quite a while building the prototypes. They include the cheap bearings I bought at the hobby store, a steel axle, and the N50 cylindrical magnets.
The acrylic models gave me a good idea of the tolerances involved, but it was clear I needed more precision. I used the dremel to finish the prototypes, drilling holes, and tapping some of them for 2mm screws. Unfortunately my drilling was not precise enough for production work.
I never install the coils more than just for test-fit in the acrylic prototypes. Amplifiers would be needed before any performance testing would be possible anyway. Eventually the prototypes proved useful in demonstrating design to the machinists that would build the aluminum pieces for the final version.