Here is a remix of Lion4H's Radial Fan Fang to be able to mount to a 40mm x 40mm hot end fan instead of an E3D 30mm fan. Specifically designed to work on a Creality CR-10 with superpotatofudge's hot end cooling duct and the stock hot end and cooling fan. Requires the use of a 5015 radial blower fan like the original design. Blender file included to allow modifications, just look at Lion4H's thing for instructions. Probably works for afinitbot and CR-7/8 as well.
Updates:
4/9/2017: Thickened fan mounting bracket that connects to the hot end fan as original was a little thin and was buckling when tightened down along the bottom of the mount.  Haven't tested yet, but shouldn't be any issues with this version.
4/29/2017: Version 2 of the no probe fang duct that mounts between the fan and superpotatofudge's hot end cooling duct. A little thicker for durability.
5/7/2017: Added new version that thickens the 5015 mounting fins.
5/27/2017: Updated photos to reflect how the thicker version should be installed. Pictures…