The extruder fan on the Davinci is not the most efficient thing in the world, so I made a shroud to make what little it does more effective. UPDATE The Extended Version replaces the finger-guard and screws into place using those screws, this stops all the escaping air and gives a much better look to the installation. You don't need to unscrew anything for the normal shroud, it just slides on (might need trimming around the fan hole, depends how accurate your print is!) There is also a hole above the filament stepper motor that needs blocking, or as you can see in some of my photos you can put another 5v fan there and wire it in parallel to the normal fan. The stock fan blows air over the extruder heatsink then down onto the part, there is actually a moderate amount of ducting to guide the air onto the part, so I am playing with a centrifugal fan blowing through the top of the extruder over the stepper motor. There is actually quite a lot of air blowing through there now... Lets see if I can actually use it as a layer fan if it is controlled properly! There are some other extruder fan shrouds on thingiverse, I haven't copied them, in fact they are what has persuaded me to make my own (I want to keep this very simple to make and install) equally I wouldn't say this is better than any other on here (actually there are some that look really good, but turn the air flow around, try http://www.thingiverse.com/thing:824926 for more info) we are all learning to make this cheap printer better! Any feedback welcome!It's a very simple print, no additional cooling needed!