Was having issues with dust on my filament and I found this screw type filter:
http://www.thingiverse.com/thing:125321
I designed this bracket to allow use of the filter with a MakerGear M2 that has been modified with this filament guide:
http://www.thingiverse.com/thing:154429

Download and print these objects:
http://www.thingiverse.com/thing:125321
http://www.thingiverse.com/thing:154429
Change out the stock or current filament guide on your M2.
Then print the bracket using support and assemble (swab the filter canister protrusion and around the protrusion base with a bit of superglue or acetone, depending on your choice of filament, and insert in the small diameter hole in the bracket, being careful not to block the filament path with adhesive. Allow the glue/acetone to bond securely. Slide the end of the bracket over the filament guide until it lines up with the desired position on the guide). Route the filament through the unscrewed filter pieces, fold a piece of filter material (I find craft brush foam tips work quite well) over the filament, tuck up inside filter canister upper and reassemble. Check/clean/change filter material periodically.