This is an optical filament sensor which works with every kind of 1.75mm filament, every colour and clear filament.
I designed this for Bq hephestos 2, but work for every prusa i3 style 3d printer
You can buy an end stop sensor
https://www.aliexpress.com/item/6-pcs-lot-Optical-Endstop-Light-Control-Limit-Optical-Switch-for-3D-Printers-RAMPS-1-4/32434841034.html?spm=a2g0s.9042311.0.0.27424c4dDT23Br
In Configuration.h search for the FILAMENT_RUNOUT_SENSOR define and comment it out
My config file is:
// Uncomment for defining a filament runout sensor to check the existence of filament
define FILAMENT_RUNOUT_SENSOR
ifdef FILAMENT_RUNOUT_SENSOR
const bool FIL_RUNOUT_INVERTING = false; // Should be uncommented and true or false should assigned
define ENDSTOPPULLUP_FIL_RUNOUT // Uncomment to use internal pullup for filament runout pins if the sensor is defined.
define FILAMENT_RUNOUT_SCRIPT "M600"
endif // FILAMENT_RUNOUT_SENSOR
I used the PIN 57
My pins_BQ_ZUM_MEGA_3D
ifdef FILAMENT_RUNOUT_SENSOR
define FILRUNOUT_PIN 57
endif // FILAMENT_RUNOUT_SENSOR
More information about the Marlin configuration can be found here.
http://marlinfw.org/docs/configuration/configuration.html#filament-runout-sensor

Bq hephestos 2

No

Yes

0.2

25