A newer quick release version of this duct with greater height adjustment is now available:
A fan duct for cooling prints which can be used instead of the standard fan duct when upgrading from the standard J Head to an E3D hot end (in this case a v6) on a NopHead Mendel90. It uses the same 60mm fan as supplied by NopHead.
This can be printed without supports depending on what printer and slicer you use. I personally printed it in Bridge but you could also use ABS. Do not use PLA because it will most likely melt.
The standard 60mm fan supplied by NopHead can be used but I used shorter bolts to stop it fouling with the belt. Also I used the standard nylock nuts on the bottom but regular nuts on the top again to allow more space for the belt. The alternative is as suggested by daichiasuka in the comments is you could flip the bolts around and recess the heads instead of the nuts.
If you have the Dibond version of the printer use FanDuct.stl. If you have the old Sturdy version we are currently working on a version for this but its still experimental.