QUBD : Bowden extruder with the original drive gear with 3/8' thread push-in connector.

thingiverse

I'm glad this device utilizes the original drive gear or "mk7", which means I won't need to update the firmware. It also accepts a push-in connector with a 3/8" thread, unlike my previous setup that used a 6mm thread. That old design had some issues - it would easily clog the filament and sometimes even pull itself off after just a few screwing and unscrewing operations. However, this new device is more reliable. If the push-in connector ever gets loose, I can simply tighten it further to secure it in place. I'm using an arm and idler setup here, which you can find on Thingiverse at http://www.thingiverse.com/thing:38281. Other compatible designs include http://www.thingiverse.com/thing:15718, http://www.thingiverse.com/thing:21686, http://www.thingiverse.com/thing:43411, and http://www.thingiverse.com/thing:53009 (which can be printed in reverse).