Filament End Sensor - Switch Support
I projected this filament end sensor to put in pause the 3DRAG when the filament is finish. So you don't have to restart from the beginning the print of your obkect. You can replace the filament and send the continue command to the printer.
You can connect the switch to a free PIN on the controller and write the relative code to put in pause your printer, or if you already have a button on your board to pause the printer you can connect the switch to that button.