Filament Travel Indicator

Simple mechanical Filament Travel Indicator
Requires
Axle:
2 mm round steel rod ~ 70 mm long
Tyre:
4 mm of Rubberized Insulation as used on hi current multi stranded power cables
(shown in red on diagram) fine surgical rubber or silicon tubing may also work
Spring:
A small amount of form rubber cut into a cross shape
(shown in white on diagram)
Filament guide:
PTFE tubing

Use the back plate screws and spring thickness to create a gentle pressure for the Tyre on the passing filament so as not to load the filament path (if you move the filament by turning the axle it's too tight)

Sliced in Cura 0.4 nozzle Fine quality