Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:3526072.

A quick demo of my new gearbox thing:3511382. A solution searching for a problem.

Print at layer height 0.2 to preserve the one-layer gap between the ring gears.

For maximum strength, print at least the rings and gears solid by increasing wall thickness rather than infill.

Separate ring gears using xacto knife, box cutter, sharpened spatula or similar before turning.

note: Not yet printed, no guarantees. Layer View preview looks OK.