Update: V2 for Cura users-
Since you can't manually place the supports, this version has built-in support struts inside the neck of the fan duct. So the entire thing can be printed without supports.
You can easily snap the struts off with a pliers after printing.
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This is a remix of juha_j's fan duct (which uses the Noctua 40x40x10mm silent fan NF-A4x10 FLX), with the following changes that I made:
1) thickened the duct walls slightly for improved rigidity.
2) slanted the "neck" of the fan holder to get a more streamlined airflow, as suggested in
cannon3d's comment.
3) lengthened the duct and added a fixing collar at the end. This way the hot air gets expelled directly out through the ventilation holes of the metal base.
I've included the .skp files (in Sketchup 2018) so feel free to make improvements if you wish.
roundisfunny
