Redsail X700/M500 X-axis endstop mount

Our Redsail laser had the X-axis flipped, things came out mirrored around X. The included Autolaser software had no way of correcting for this (!), so we decided another fix.
Adding another endstop allowed us to flip the axis in firmware settings.

Slips onto the carriage without screws. Recommend double-sided tape to make it not so easy to lift off.

Github: https://github.com/jonnor/projects/tree/master/practical3d