Magnetic filament monitor case with switch integrated ?

[BoA]

Is there any STL for magnetic filament monitor case with transoptor/switch integrated?

I would like to have monitor to react immediately for end of filament instead of waiting for no filament movement report.

I have reversed bowden setup, and extruder is basically not able to push pack enough filament so it can not be removed without disconnecting tubes.

I would imagine, that sensing position of sensor idler (this element on spring) is easy task, but I could not find any sensor casing that has this implemented.