I figured it would be a good idea to combine both a 40mm fan heatsink fan shroud and the well known fang already modified to fit the shroud perfectly without the guess work of modifying the fang for those new to 3D printing and/or blender.
I remixed the original 40mm fan duct by loco to make it easier to snap on without breaking and stay in place without shifting up.
I also adjusted the Fang by Lion4H to fit the nozzle position and thickened the support arms connecting the fan mount to the fang arms.
This uses a 5015 radial fan and a 40x40x10mm brushless fan.
The hotend needs to be an E3d v6 or clone and the length needs to be about 46mm (minimum 45mm) from the top large fin on the heatsink to the tip of the nozzle (see included diagram). I'm using an E3D V6 clone for this but I have been told that it also works well with the V5 stock hotends.
Update 20170903 - Added a shroud with a stay on screw (see my Removeable X Carriage System - https://www.thingiverse.com/thing:2515055).
Also modified the Fang so the mount plate will be sandwiched between the fan and shroud to decrease rotational momentum (the 40x40 fan mounts on the outside of the assembly). Also included the blend file in case you want to print versions with the sensor mounts.
Update 20180403 - Added a version with the radial fan mounted 90 degrees on Z and straight up. This is purposefully built for my I3 Cube/HyperCube Evo hybrid where the original fan mount would not fit. As with the other versions, I recommend using it with my hotend mounts that has a screw in point for the hotend fan shroud. I'll be posting the same mounts for the Cube/HEVO.
Update 20180405 - Reorganized the files and removed the older version.
I recommend PETG for this.
Minimal supports needed for the Fang. Also use a brim to prevent it from falling over during print.
No supports needed for the fan shroud.