I wanted a strong thin key ring for my computer bag. I needed it to be thin enough to thread through the nylon straps.

• ring diameter on center 30 mm (inner 25 mm, outer 35mm)
• ring thickness diameter 5 mm

Add a comment if you would like to see other sizes.

Most key rings have one or two large hooks to keep the ring closed. This design implements many reverse hooks throughout the inside of the ring to distribute the load.

My Bambulab P1P is precise enough at 0.08 layer height to print with a 0.2 mm gap between the rings. You may need a knife to separate them carefully. 

I've also included a 0.3 mm and a 0.4 mm gap version.