Remember the Igus drylin bearings that everyone has been talking about? I just discovered they do a 3d printing filament: so you can print parts that slip easily and resist abrasion. http://www.igus.eu/wpck/15341/3D_Priting_Material_Startpage
This opens crazy applications... We could dual print the carriages with integrated bushings for example . Depends on how this reacts when printed on an other material like Edge or XT...