These days, all new extruders (J-head, E3D, Makerbot & more) have a separate fan that is cooling the upper parts of the extruder. After fixing the 4th plug in an eve, I realised that I really needed this as well. It took just 15 minutes to make & print, but here it is for others to use as well.Print the mount, fasten hex nuts by pushing/knocking them carefully in place, push the mount through the main screws, affix fan and enjoy trouble free printing!To drive both the normal fan & the extruder cooler, I made a Y-split cable using JST plugs from ebay. Just search for "2 pin jst" and you'll find them. If you're enclosing your Ultimaker for ABS printing, this is especially useful to prevent plugs but it also allows you to safely go a little higher than you normally would.