I wanted to print this at 0.3mm layer height for a quick print and even the loosest inner ring was too tight. I couldn't work with the original topology easily (it was constructed with booleans) so I remodeled and shrunk the inner ring in both directions. Now it actually spins and I can also get the outer ring on and off for reprogramming rather than it being stuck on forever.

Great project though, go check it out:
https://www.thingiverse.com/thing:3047658