The 2.0 version of this is better and can be found here: http://www.thingiverse.com/thing:260558 This can be used wherever a direct drive bowden extruder is desired. With hole for push fit connector. I had problems with all the spring version extruders. Initially they would work but after a few months they would lose compression and start glitching. So I built an extruder loosely based on Joe Chung's remake of Whosawhatsis' minimalist extruder that uses a screw instead of a spring. I still wanted some flex though to allow for the possibility of some filament with low diameter tolerances so I use an M4 screw to apply tension and use about 5-6mm thick piece of rubber cut off from a rubber plug found at the hardware store for $1. In order for the M4 screw not to dig in to the rubber, use an M3 washer between the end of the screw and the rubber. This is designed to work in conjunction with my mounting bracket for a Cerberus (Rostock style) Printer found here: http://www.thingiverse.com/thing:159478 It could also be mounted directly to an aluminum extrusion with appropriately sized T-Slot nuts.**Notes 1) Use a 12mm M3 screw to hold a 623 bearing in (M3 self taps) 2) Tap the push-fit connector hole with an M5 screw before screwing in the push-fit.