I have seen these (in brass) on boats and some high-end luggage, such as the 1870's English officer's wood luggage he used when going off to India.
The mounting holes are based on a #5 x ¾" Steel Phillips Flat Head Screw for Wood. They cost $6.94 / 100 from McMaster-Carr, PN 90031A131
I did not use supports and the holes came out surprisingly well. The pin is press-fit into the ring's hole.
The Retainer Pin is press fit into the Finger Ring. Four different diameter pins are provided under “testpins” file so that the best press-fit pin can be installed.
The author marked this model as their own original creation.