The model
Each ring hangs with two conical pegs in conical dimples of the next larger ring. The pegs engage 1.8 mm deep and have 0.4 mm of clearance; the lateral play of the rings is below 0.6 mm, so they cannot slip out of the dimples. The axes alternate lengthwise and crosswise, turning the flat disc into a sphere of rings.
All surfaces between the rings are spherical surfaces around the same center, so the gap of 0.5 mm stays the same in every rotation. Checked are 24 positions per joint over the full turn and 30 random overall positions of all rings, with no contact.
The stand is a second, simple print part: the outer ring stands upright in a groove while the inner rings turn freely in a recess.
View print notes (German)
Print notes included in German; part names are self-explanatory.