Smart Filament Microswitch Sensor

This is a simple, mostly single piece filament monitor using a cam actuated microswitch. With the hob I used, 34mm is the distance filament travels between clicks, and has worked fine as the configuration for klipper. I just put this together "temporarily" from parts I had lying around, but it proved reliable enough that I didn't bother making a better design, but I hope for remixes of this. The idea is to have a smart filament sensor out of simple parts almost everyone will have lying around from printer maintenance and upgrades.

Parts:
- 1 x M5 screw (for the axle, long enough, excess doesn't matter)
- 1 x M3 screw (for the clamping roller bearing, too long will interfere with the cam)
- 2 x M5 nuts
- 5mm ID extruder hobbed gear
- 1 x 3mm ID, 10mm OD bearing
- 2 x 5mm ID, 9mm OD bearings
- 1 x microswitch
- 2 x 1.5-2mm wood/plastic/self/tapping/M2 screws for the microswitch
- wire the switch
- 2mm ID, 4mm OD PTFE tube
- 4.0mm drill for clearing the mounting h