Filament cleaner for Ultimaker

-EDIT- I've taken the files to YouMagine.com since Makerbot has joined the dark side: http://www.openbeamusa.com/blog/2014/5/22/stay-classy-makerbot

https://www.youmagine.com/designs/filament-cleaner-for-ultimaker

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