These three rings represent three different fits, and a different way to approach each one.

The Rings are designed to be 3d printed in silver, and make use of their tolerances. 

The Tight fitting ring screws onto the users finger. the loose fitting ring is like a finger trap and only tightens when someone attempts to remove it. The ideal fit ring has a structure that allows some flex, so it is only in contact with the finger when required.