Under £2 Filament Runout Sensor

##YOUTUBE VIDEO BELOW FOR ASSEMBLY##

A very cheap and easy-assemble filament runout sensor.
Print at 0.1mm layer height and use a horizontal size compensation of around -0.15 (or whatever suits your printer).
- Has built-in dust filter
- Has override power switch
- Screams at at least 80dB when filament runs out

##Parts List##
Piezo Buzzer: https://www.ebay.co.uk/itm/181778719109
Slide Switch: https://www.ebay.co.uk/itm/252106861027
Wheel Microswitch: https://www.ebay.co.uk/itm/281854711611
M2.5 10mm Screws: https://www.ebay.co.uk/itm/161716606652
+
4x LR41 1.5V button cell battery
Thin wire
Scrap metal for battery contact