Filament runout sensor Prusa Mk2 style extruder

I needed a runout sensor I could mount directly to the top of a MK2 style extruder body. I wasn't happy with the ones that were available so I came up with this. It's inspired by the new MK3S filament sensor setup.

It uses a steel ball for the filament to ride on so that the filament won't kick the sensor off on unload. The ball housing has a fin that triggers a optical sensor. Ball housing needs to be printed in BLACK for it to trigger the sensor. The ball is a tight fit, I use PETG filament