If you are not able to get the rings rotating freely, you can use the "looser-tolerances" version.
Model By Marvin On Printables
https://www.printables.com/model/7876-rotating-rings-toy
@CRAFTA_3D
rotating-rings-toy.stl | 7.6MB | |
rotating-rings-toy_looser-tolerances.stl | 7.6MB |