Simple SCAD script that generates a duct plate & length of duct for mounting to a small DC fan (25mm - 120mm).
You can generate square, conical, or round ducts.
I tried to make the design printable without support although you must be carefull if using the cone setting not to make an unprintable overhang.
I have included 4 sample STL outputs but you will have to generate your own to suit.
Ive not made this a library style file (yet).
Uses my fan mount library v2 (http://www.thingiverse.com/thing:18273).
Parameters are commented in the SCAD file thus...
fan_size //25,30,40,45,60,80,120 are the supported values
thickness_mount // aim for a multiple of your layer thickness here
duct_diameter //check this so duct dia never more than fan size - (2 x duct thickness)
duct_diameter_2//only used if shape is cone
duct_shape = "round"; // "round", "square", "cone" (round is default, make sure you include quote marks)