This is an adapter that allows transitioning from 2 80mm cooling fans to a 4" standard dryer duct. You'll need 8 small screws to attach it to the fans.
This was inspired by the Da Vinci 1.0 Fan Mount (http://www.thingiverse.com/thing:634403) and I designed it to pair perfectly with it, attaching on the opposite side of the fans and allowing you to vent exhaust fumes to the outside through the dryer duct.
I printed the fan mount and this, attached them to the fans, inserted it into the Da Vinci handle hole, attached the dryer duct to this adapter, and routed the other end of the duct through a hole in a board I placed in a window. This setup has eliminated all of the ABS-printing smell (and arguably dangerous fumes) from my area.
I printed with no supports and it turned out great.