It may be a good idea to lead your filament through a sponge to automatically clean off dust, hairs etc. Couldn't find one for my Ultimaker, so I made a very simple one with OpenSCAD. I think the sponge causes very little friction, so no issues with printing and retraction. I'll see how it goes, maybe change the design a bit.Using the scad-file it's very easy to change dimensions if it doesn't fit your printer or if you want a different thickness etc. I made some stl-files with and without screw attachment and square cutouts.cleaner.stl - simplest one, just clamp it on the filament feeder cleaner_screw.stl - can be attached to the feeder using a screw that's already there cleaner_squares_screw.stl and cleaner_squares.stl are the same with some squares cut out in sides and back to make it even lighter. More difficult to print though.Cut a piece of sponge and feed the filament through.Just a copy of my thing at http://www.thingiverse.com/thing:133353 :)