A sponge wipes the filament clean from any dust particles and prevents them clogging the extruder.By dropping a few drops of common mineral oil on the sponge the filament passing through gets lubricated thus relieving the extruder motor from strain.Lubrication is specially useful if the filament needs to travel through long tubes before it enters the extruder.INSTRUCTIONS3D-print the provided STL file and insert a small piece sponge into the filament filter.Poke a hole into the sponge and make sure the filament passes through and comes out at the other end.Soak the sponge with a few drops of mineral oil (as for sewing machines, door hinges or bicycle chains).Place the filament filter somewhere in between the spool and the extruder. If you have a plastic tube which guides the filament to extruder (such as a bowden solution) make sure you place the filter before the filament enters the tube.See video for more information- http://youtu.be/rMDEsrgzC9MBy Creative Tools- http://Creative-Tools.com- http://google.com/+CreativetoolsSe- http://twitter.com/CreativeTools- http://facebook.com/creativetools- http://youtube.com/creativetools- http://instructables.com/member/CreativeTools