Parametric Measuring Stars

Remix of [Ken Hackbarth](http://volksswitch.org/)'s [Measuring Stars](https://www.thingiverse.com/thing:3221145) in OpenSCAD so we can measure pens for demoing the [Parametric Finger Pen Holder](https://www.thingiverse.com/thing:3630486).

Supplied are two measuring stars, one for 5–9½ mm diameters and the other for 10–14½ mm.

If you wish to change the ring gauge sizes, lines 9–10 of the source have the dimensions you need to change:

min_diam = 5; // smallest ring diameter
diam_step = 0.5; // increment between ring sizes