Simple Optical Filament Runout Sensor

This is the result of a weekend project. 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 maybe design another one with a mechanical enstop in the future.