I don't own calipers yet, so there's likely a couple of dimensions that are off.
The keychain ring inserted is a 2.5mm x 2.5mm x 25mm diameter torus, just put a pause point in the slicer
Recommended print settings: https://www.printables.com/model/12586-ninjaflex-profile-zero-stringing-flawless-print-be/comments/1523620
3rd picture is not in the model, its my personal variation of the back design (can probably tell a lot about me from that)
The author marked this model as their own original creation.