My sister likes to sew and often bags. Once she saw a lock that she and my niece would have liked. She wasn't able to take a picture but she gave me a rough sketch - to be honest two lines each representing one perspective. I detail this drawing through a perspective view and we confirmed on it.
After that it took only a short time in Fusion 360 and I printed some variations of the design. Thicker, thinner, tighter etc. And guess what:She's happy.
Don't take the "secure" to serious. It's only added to visualize that the ring will less likely slip out of the clip on it's own easily. Because of this you might need to hands to open the fastener.
You want to alter the design? Bigger, smaller, rounder? Lucky you - I've added the Fusion 360 and the Step File. This should make it easy for you to alter the design.
If you're interesting in this design, you might want to have a look here, too:
Fastener for bags, handbags, backpacks etc. - "secure" version: https://www.thingiverse.com/thing:3094813
Spool tool for sewing machines: https://www.thingiverse.com/thing:2442212
Ladder Lock / Ladder Buckle: https://www.thingiverse.com/thing:3135967
D-Ring for bags, handbags, backpacks etc.: https://www.thingiverse.com/thing:3253789
Das Filament PETG