This is my idea for a filament filter, it celans the filament, reducing the risk of jams with smaller noozles.

It has to be assembled inserting a small piece of spongy material inside the extruded cilinder (the chimney), be carefull and use something clean!

I suggest to make the hole for the filament in the sponge before mounting it, this way you eliminate the risk of pushing sponge piecs into the extruder gears.

Print instructions

no support needed, easy print, 34 minutes.
low infill is ok.