I still can't find a limit switch that is compatible with the Ender printer and a sensor for detecting when the consumables on both sides of the pipe are exhausted. So, I designed and made such a sensor by myself.

You need a limit switch for the Ender printer, a short piece of 4 mm diameter PVC pipe, and two short M3 screws—I used the two screws that originally fixed the limit switch. These screws can be directly screwed into the plastic parts without the need for additional tapping.

Important notice:
If you want to enable the automatic unloading function when the sensor is triggered, you must bend the end of the metal arm appropriately so that it can press the button when the consumables are exhausted and released. It is recommended to conduct thorough testing before formally installing the sensor to ensure optimal performance.