Filament sensor/guide for Ender 3

While ago I installed bl-touch on my Ender 3 and was left with a spare z-axis endstop so I decided to use it as a filament sensor (from software and electronic point of view I followed [this tutorial](https://youtu.be/gwHpXaj_6xE)). I looked through many such solutions already available but I wasn't happy with any which led me to design my own and here is the result!
In this design I combined the function of filament sensor with filament guide and apart from functionality I also tried to make the result look as aesthetically pleasing and as simple as possible so it only uses few screws and few easily printed parts.
So far it has worked great, so I hope it can be of some use for you too!

Parts needed:
* 2x M5 screws - 20mm
* 2x M5 nuts
* 2x M3 screws - 20mm
* 2x M3 nuts
* 2x M4 screws with T-shaped nuts (the ones from the original endstop part can be used)
* 2x 608 ball bearings

3D printed parts:
All necessary parts are bundled in all.stl with the mount to the frame angle