Print-in-place stackable filament jam and break detectors/sensors

Cheap as only one end stop is needed;
Simple to print as it is print-in-place. 
Stackable so you can use it on your multi-toolhead machines

It can detect both filament jam and/or break using one endstop switch.

20240822: ver. 2 with more strength to the printed spring, less likely to give false alarm

PS. The idea of using one microswitch to detect both filament presence and jam is from martin_au in here: https://www.printables.com/model/58207-super-simple-filament-jam-and-presence-sensor . While my design is utilize compliance mechanism to reduce the needs of hardwares like preload spring and screws.