Filament sensor
thingiverse
Microswitch enthusiasts can snag affordable options at dx.com or banggood.com, where tiny switches go for next to nothing. Simple filament sensors are a great fit for these bargain buys. Connecting one of these sensors to OctoPrint on a Raspberry Pi is a breeze. They're specifically designed with these microswitches in mind: http://www.dx.com/p/diy-0-5a-125v-250v-micro-switch-black-10-piece-pack-120309
Download Model from thingiverse
With this file you will be able to print Filament sensor with your 3D printer. Click on the button and save the file on your computer to work, edit or customize your design. You can also find more 3D designs for printers on Filament sensor.