RepRapPro Huxley Dual Head Mod

Parts required to upgrade your (RRP) Huxley to dual heads.
Designed to not limit printing size and use standard head parts.
Writeup here: [Reprap Forum](http://forums.reprap.org/read.php?214,390455)

Two "Extruder Mount Bar"s move original extruder motor away from frame by about 5mm, and allow mounting of 2nd motor on other side - it's longer to account for non-symmetrical geometry of extruder drive.

Print one of everything and make the Nozzle Bock in Aluminium from the PDF drawing. - D