CNC 1610 Improvements

This project contains 5 improvements for a 1610 CNC. These improvements were
inspired by the following YouTube videos of JJ Hontebeyrie:

* https://www.youtube.com/watch?v=NNrqx62lyBI&t;=602s
* https://www.youtube.com/watch?v=_gX_YCsN4wo

**1\. Extrusion slot covers**

I've used the following project to cover most of the extrusion slots:
https://www.thingiverse.com/thing:4641897 . Print the 100 mm long one and
scale it in the slicer to get the length you need.

**2\. Z-axis endstop**

The sensor must be plugged on the Zen pins of a Woodpecker GRBL board. You
will need the following material:

* One EndStopZBumper.stl printed part
* One micro switch. You can remove the one on a Makerbot style end-stop.
* One M3 x 20 mm screw
* One M3 x 5 mm brass insert
* Some wire, terminated with Dupont female connectors at one end
* Some Super Glue

**3\. X-axis endstop**

The sensor must be plugged on the Xen pins of a Woodpecker GRBL board. The red
wire