I happened to like this extruder design, but there was no fan shroud design for a blower fan. Until now! This is actually a third iteration of the shroud, I'm getting some great results printing (and cooling) PLA with it. The fan i've got is from E3D (http://e3d-online.com/Electrical/Fans/50x50x15mm-12v-DC-Side-Blow-Fan) The whole thing is also designed with E3Dv6 hotend in mind, may be too low or high for another. 2015-10-19 edit: I fixed the issue with the shroud mesh, should slice perfectly now.Enjoy!Print this with ABS or other high-temp resistant filament. Holder is easy, shroud will need printing on supports (use only "touching bed"!) and involve some bridging. You'll need a small screw to connect the holder and shroud, 10mm overall length and 3mm diameter. Be careful, the hole on holder side is perpendicular to layers, I had to super glue it after I overtightened the screw. You'll also need two M4 screws and nuts to secure the fan to holder and one M3 screw and nut to mount this whole contraption to extruder body. I don't remember exact lengths, but I'm sure most reprappers will have a selection of these.