I wanted to use this Fan Duct, http://www.thingiverse.com/thing:295317, on my qidi printer which is a flashforge creator clone which is a markerbot replicator dual clone.

In order to use that Fan Duct I needed super long M4 screws which I do not have and do not want to wait 3 weeks to be delivered. I wanted to modify the duct but I was having no luck playing the import export game with multiple CAD software to get the model into sketchup.

Then I stumbled onto this, https://www.thingiverse.com/thing:486566, which worked pretty well but had not height adjustment. So I decided to create something similar but to use the 2 slits above the bearings to secure the bracket and being able to adjust the position of the duct.

The 2 nubs that poke out on the bracket fits into the 2 slits above the front bearings, it provides a secure hold. The bracket mates to the duct via two M4 bolts, you can adjust the height of the duct. There is very little sag on the duct when using the bracket so you can get the bottom of the duct to be as low as the extruder nozzle outlet without interfering with your print.

When you print the bracket I suggest you rotate the print so that the nubs face up, you will need to print with support. If you have the nubs face in another direction then you will need to put support material around the nubs and you will spend your time meticulously trimming support material around the nubs to get it to fit into the slits above the bearings.