Modded MK3S Extruder

This is based on the new R4 or MK3S extruder set and modded to be used with [1A125VAC microswitch](https://www.thingiverse.com/thing:3438084) as the filament sensor. It would take months to have the prusa's filament sensor hit the conventional market.

I designed this because I am sure that the prusa's optical endstop won't be available that easily and I wanted to use with hardware that can be sourced easily.

Main difference between original extruder for MK3S or R4 and this MODDED is:
- Uses ball point spring OD 6mm max instead of magnet slab
- Uses [1A125VAC microswitch](https://www.thingiverse.com/thing:3438084) Instead of Prusa's custom optical endstop
- Uses 3D printed ball end for those can't find metal ball bearing in their area
- Can use normal hex M3 nut instead of only square M3 nuts (on some slots)
- Can be used with cheap chinese instead of only original e3d (explained below)

This time I am not going to bother adjusting for non-bondtech gears. I also didn't cove