Parametric Ring Sizer (metric)

Finger size gauge (measuring ring) to find out the size of ones ring. Can be customised for any circumference. It uses no rounding or table, just straight up calculation but it is lost in printer precision limits anyway.

My printer was not printing it to the required tenths of the milimeter. Rotary tool + sandpaper and Vernier caliper does the job.

Upstream:
https://github.com/mhradilek/things/tree/master/ring-sizer