2020 Mountable Optical Filament Sensor

Remixed from the optical filament sensor at http://www.thingiverse.com/thing:1646220 but modified with two M5 holes to allow it to be mounted to a 2020 extrusion.

It uses a no-name optical endstop (like this one http://www.geeetech.com/images/v/Geeetech_IMG_5412.jpg) switch and just "guides" the filament threw it.

Endstop is connected to a Rasperry Pi running Octoprint, which is handing the correct parking and resuming by using the Filament Sensor Plugin http://plugins.octoprint.org/plugins/filament_sensor .

Works with all 1.75 mm filament (you should be able to drill it up to work with 3mm), except transparent ones.

I've also added a version where the holes under the sensor electronics are threaded for M3 screws to hold it in place.

I also have one that takes an M6 threaded bowden connector on the output. I recommend printing that at high quality for the threads to work, though.