RigidBot R1 Z-Axis "EASY END STOP"

Original Kickstarter RigidBot R1, has a fixed distance between the bed and the hotend. Any regulation has to be performed moving the position of the ring containing the Z-End Stop switch, or even worse, you may need to touch the 4 bed alignment screws.
That is not very comfortable, especially if you plan to install a glass over the bed, and continue to swap it at any print.

This addon, adds an adjustable end stop knob as found in many RepRap printers.
This is the result of many hours of des