My wife likes me to print rings for her whenever I get a new color of filament, and keeps them in a certain order to swap them out day-to-day. So I came up with a solution to keep them together, in order, and where the cats can't cast them everywhere.

The main model uploaded here is the retainer. Print it out of TPU so it can flex. The rod and nuts are from “Nut Job” by mattala found here. I used the 100mm rod, but made an 8.5mm nut since the included 9 was a bit too loose.

Print 1 rod, 4 nuts from PLA or PETG (which I used), and 2 retainers from TPU. Thread one nut, followed by the retainer, and a second nut. Use the inner nut as a jamb nut to lock it all in place, on both sides. Then you can simply push a ring over the flexible end to fill up the holder, and pull it from the other side as you cycle.