Greg's Hinged Accessible Extruder with Herringbone Gears for 3mm filaments.
Great update to the Greg's Wade Extruder, includes higher precision Herringbone Gears.
This extruder will fit the MakerFarm Prusa 6" i3 and MakerFarm Prusa 8" i3 Kits.
I usually print Extruder Parts at 0.2mm Layer height, 40% Infill (which might actually be more than I need), and with 3 Perimeters. I also prefer honeycomb fill pattern, because it looks cool when it's printing, and I suspect that it gives the parts a little more stiffness. (ZennmasterM)
To assemble watch the following video by Colin Farrer