The main concept behind the modification is the optimal PTFE tubing configuration. It follows E3D's recommendation : http://wiki.e3d-online.com/wiki/File:V6_Assembly_-_Half_a_Wades_Block.jpg PTFE tube goes inside the extruder, reaching very close to MK8 gear. Filament is exposed as little as possible for optimal flow. Tube stays stable and locked at both sides. At outgoing side by the E3D plastic pneufit provided by "E3D full kit with bowden add-on" and by a M4 nut at ingoing side. Be aware, M4 nut will press the PTFE tube making its I.D. narrower. Dont forget to drill with 2mm bit inside the tube, for the whole narrow part of the tube, to restore its I.D. at 2mm as it should be. Otherwise there will be an increasing friction bottleneck for filament flow. Extruder's base made longer to provide easy access at mounting holes. The idea for this mod came from here : http://www.thingiverse.com/thing:661936 For my printer's extruder, I used and recommend this modified idler for more tension against mk8 gear and thus even better flow of filament: http://www.thingiverse.com/thing:487891 Extruder results are satisfactory. Tested with PLA and ABS, it can drive filament without any missing step even in higher speeds although my NEMA motor is not strong enough (holding torque 2550 g-cm). In action, printing an object at 70mm/s speed: https://www.youtube.com/watch?v=fvsaoYTabMs&feature=youtu.be My extruder's complete parts list, in case it helps anyone: Hotend Fan Recommendation: I replaced original 30mm E3D fan with a 40x40x20 mm fan running at 7v instead of 12v. This way noise and hotend vibration of E3D fan is gone, producing better quality prints and less noise headaches. To get 7v from ATX PSU you can connect fan's negative to 5v and fan's Positive to 12v. Thanks to Airtripper for publishing this very nice piece of openSCAD source. Happy printing ! Update 12-May-2015 Redesign uploaded. Inbound and outbound PTFE holes are lowered by 0.5mm to eliminate tube declination.