Fan duct

Work in progress for a fan duct for my Prusa i3 Takes a 60mm fan.

to replace the duct for
http://www.thingiverse.com/thing:119616

modelled after
http://www.thingiverse.com/thing:91931
but much more poorly designed. ;)

Update:
Channel to direct more air around the back of the fan.
Better Default size for the stl
More parameters for the scad.
vent supports to reduce sag from heat