Connect a PTFE to your 3up printer to allow for easy feeding of filament. Uses this part: http://www.filastruder.com/collections/e3d-spare-parts-and-accessories/products/bowden-couplings-threaded-1-75mm and the ptfe tubing: http://www.filastruder.com/collections/e3d-spare-parts-and-accessories/products/ptfe-tubing Use a drill to carefully enlarge the hole in the extruder so it is a tight fit (practice on a scrap first to find the right bit). I drilled down about 6mm. Pair this with a filament spool roller bearing and have jerk-free filament feeding: http://www.thingiverse.com/thing:366486 Remixed from here: http://www.thingiverse.com/thing:17234