For use with Prusa i3 Rework X-Carriage. The inspiration came from ch1t0's i3 extruder design. I initially began designing this extruder to work with the E3D Hotend because of the sloppy fit on the original version but the one thing I really wanted, was to install 60mm cooling fans. In addition I design a E3D 40mm shroud that works with v4, v5., plus a Dual 50mm Cooling fan holder and a 60mm Cooling Fan Holder. 2 different clamps, one is just plain and other one has extension for addons you want to put on. Fan Cover used: i3 40mm Fan Cover and Open Hardware 60mm Fan Cover. Other parts I used - RichRap's Guidler with Lever and schlem's Skulltruder Gears. Funny note: When I started the 60mm fans (I know, OVERKILL) it sounded like a jet engine and for a split second I thought my printer was going to start hovering above my desk. :) Update: Feb 8, 2015 Added v6 version for 3mm filament and also a v6 40mm Fan Shroud.It's pretty straight forward but if you need instructions. Go here: http://reprap.org/wiki/Prusa_i3_Rework_Extruder_assembly Note: If you decide to use the modified version, you'll need to re-adjust the position of your Y-Axis endstop. Z-Axis endstop will also need to be adjusted on both versions.