Parametric ring sizer

Wrote a quick script to generate a tester ring. You can optionally include the ring size as a label on the side. Note that I've only included half-sizes from 1 to 13; the script allows you to generate quarter sizes from 1 to 16 if you need them.

***Note*** that to save some time, the ring size conversion is *calculated* rather than *referenced*. This leads to variation in the sizing very slightly from the "true measurement" as seen in the table below:
`Size True dia Calc dia Difference`
`1 12.37 (baseline) 0.00`
`2 13.21 13.2 -0.01`
`3 14.05 14.03 -0.02`
`4 14.86 14.86 0.00`
`5 15.7 15.69 -0.01`
`6 16.51 16.52 +0.01`
`7 17.35 17.35 0.00`
`8 18.19 18.18 -0.01`
`9 18.99 19.01 +0.02`
`10 19.84 19.84 0.00`
`11 20.68 20.67 -0.01`
`12 21.49 21.5 +0.01`
`13 22.33 22.33 0.00`
`14 23.16 23.16 0.00`
`15 24.00