My previous model was a bit rough and kind of bad on the back stroke. This one is made to be more print friendly. The size of the ring is 53 (EU size; inner diameter 16,9mm).
I post 2 models. One is what I use. The other one is mentioned for customization. You can customize it by using cut tool in Prusa slicer. See pictures to see what I mean. The model for customization has 3mm thick base (pick thickness) and 20mm long ring. Scale and cut to suit your needs.
I also recommend to increase the Z lift to 1mm min. If you print in default position the ring have tendency to bend before it gets closed. I noticed few collisions with default height. I also printed with 100% infill.
The author marked this model as their own original creation.