Many moons ago, I saw a picture of an old (possibly centuries old) brass key ring that kept the keys in place with rotating discs.

After a long time of the idea noodling around in the back of my head, the construction suddenly clicked, and (after a few iterations), this is the result.

Step 1: The Things You Need

I cut the key ring from 3mm plywood, and used a piece of 3mm thick bamboo dowel for the axle, and a drop of wood glue.

The files you need to cut your own are all attached to this step as well, so you can cut your key ring out of whatever materials you like, with whatever tools you like.

Step 2: Assembly

When you have cut your pieces, press one of the small pieces onto the bamboo dowel. The ring is sized to be a snug friction-fit.

Then slide on the first of the notched discs, then the main loop, then the other disc and the last small ring.

As you can see, the axle was far too long to be useful. I roughly trimmed it, then marked it more carefully before dismantling the keyring and trimming the axle to the right length.

I reassembled the key ring, this time with a drop of glue to hold each of the rings on the axle (be careful not to glue the notched discs onto the axle - they need to turn freely).

Step 3: Using the Key Ring.

Most of the time, the two notched discs turn freely and don't line up.

With the main loop on the left, line the notches up on the right, and put the blunt end of the key into the notch.
Turn the key and the discs together, and the end of the main loop with thread into the hole in the key.
Keep turning until the key slides out of the notch and onto the main loop.
Turn the discs to misalign them again, and you're done.

Keep repeating the routine, and you can fit quite a few keys onto the main loop.

Step 4: Finally...

The original key ring I saw was brass for a reason - although this key ring works well, I don't think it would last long under normal use in plywood.

If you have the capability to make one in a stiffer, stronger material, I would love to see it. In fact, I have a full one-year Pro membership to give away to the first working full-metal version posted.