Based on ring size to diameter calculation
Generates models for ring guages US sizes 0 to 16, inclusive, in quarter size steps.
Includes a hole in the corner to thread your set onto a string for easy management.
Includes a fillet on the interior for comfort.
Includes inset ring size numbers for easy identification.
If you like it, please check out http://marginallyclever.com/
First I designed it in Fusion360 and almost uploaded 10 different versions.
I wrote in the description "if only this was a customizer" and thought "hey, wait a minute."
So then I redid it in OpenSCAD.
Neato, Great story.