Big thanks to [CloudJ] for original post!

The main change I made is to the width of the gaps in the "outer" tube. Made 'em wider by about 1mm total. This allows "inner" tube to fit nicely and everything spins easy. I needed this to spin easy enough for both the very young and the very old. Works great. See my 4-ring version here: https://www.thingiverse.com/thing:5696580

In this remix I've adjusted the nubs and the tube-dimensions as my prints were coming out too tight and gap widths. Now it's smooth and easy. NO SANDING NEEDED.

Print: (1) inner (1) outer (6) locks (6) rings

I'm printing on Draft mode without supports.