Hypercube Evolution DIY Z Probe

Allows you to use an optical endstop as a Z-Probe in marlin. Configuration is for a Hypercube Evolution but can be used on a Prusa I3 type printer with minimal modification.

I used the spring from a pen to keep the tension on the extruder mount.

https://www.youtube.com/watch?v=RACh7JfYsy0