Rostock Max EZStruder Heatsink Mount
Mount a heatsink and fan to the back of your NEMA17 extruder motor. Recommend using a thermal compound such as Artic Silver 5 to improve thermal conductivity. Wire this to any 12v source available, I tapped into the extruder fan so it is always on when the extruder is hot. I had issues printing PLA with my E3D as my extruder motor got to around 50c and softened the PLA enough to cause jams, this cooled my extruder enough, along with some other mods (mostly mchackneys nozzle bore modification) to be able to print smoothly with my E3d and PLA.
The slot on the side is a for an M3 screw to secure on as well as clearance for the motor wires.
http://www.amazon.com/gp/product/B00H8QRFU2?psc=1&redirect=true&ref_=oh_aui_detailpage_o07_s00