This is a shower ring that's based off of one we had in our shower. I made this in FreeCAD and printed it on my RepRap.

NOTE: Even though I have this connected to a master link and then another shower ring, this piece has enough flexibilty to be put directly on the shower rod and still clamp shut. I printed it at 30% infill.

1. Print!
2. Get rid of strings between locking arm and lock slot. (small flat head works great)
3. Mount!
4. Attach curtain and lock!
5. Shower!