Filament sensor

this is a very simple and fast to print filament sensor,
you just need an end stop sensor, I used the one I had laying around from my tarantula 3d printer see picture and size.
and you need 2 m2 bolt with nuts, 20mm would do the trick.

Then just solder the 3 wires and all done. + left, - center and signal right.
maybe you need to experiment with the plus and -, just make sure the signal is correct.
you don't want to damage your board. wrong + and - connection will result in the computer telling you there is no filament even is there is, or the other way around
I've connected it to my LCD display

Printing this with the arrow facing down on the heating bed gives best result for me.
the inside has to be clean.