12 mm tact button solder jig

I'm going to be soldering a *lot* of 12 mm momentary buttons onto cables soon and so it was worth making a jig. This isn't perfect, but it's a good start for holding the cable and separating the ends.

Probably best to print this in PLA.

v1.1: added eject hole under button for when tolerances are too snug (at suggestion of Jake at [Makers Making Change](https://www.makersmakingchange.com/)).

v1.2: added tiny tolerances around button as people were complaining about it not fitting.

**M