I needed an ECAS Sherpa Mini and stumbled across diedirk's great model with the Zero mod built in. Needing a filament sensor as well, I modified the front housing and the lever arm to accommodate an external microswitch.
Use a brass insert in both the upper and lower holes on the arm with M3 screws. The top sensor screw will allow fine adjustment.
With no filament, the switch should be pressed. With filament, the switch should not be pressed.
The author remixed this model.
Added microswitch for filament sensor.