Ender 3 filament guide and sensor

A filament guide and runout sensor in one, with an M6 fitting to use a section of bowden tube as a inlet guide.

It aligns perfectly with the stock extruder / aluminium extruder's inlet hole so that inserting filament becomes easy from any angle. The cap fits over the top to create a continuous tube from the bowden coupler to the extruder.

I used the factory Z limit switch (I use a BLTouch instead) with the microswitch flipped over and tweaked the lever slightly - in hindsight i could have made the base thicker and mounted it upside down, nevermind, next time...

09 Feb Edit: I've been using this for a couple of weeks now, makes changing filament so much easier - don't have to stick your head round the back of the printer to guide the filament through a couple of holes any more.

16 March Edit: I've uploaded the fusion 360 file.