10 Inch Mini Rack Air Duct 120mm (1Ux2 & .5Ux2)

This is an air duct for pulling fresh air from the front and blowing it up under the equipment vs the normal face mounted fan that pulls air to the back. It should hold any 120mm case fan. You could also print another and place it upside down at the top and vent the hot air out from the top via the front as well.

The standard size takes up 2U of space total, 1U each.

The slim size takes up 1U of space total, 0.5U each.

Standard 120mm fan thickness is typically 25mm, a slim fan is typically 15-16mm. The slim model should have exactly 19.3458mm of space from the mounting plate to the top to be flush. Thus a slim fan will stay within the boundary of the half U slot if space is limited.

Material used should be something that can handle the heat, depends on your setup. PLA might work for some, but PETG or better would be best. For the Slim model a pressure optimized slim fan like the Artic P12 Slim would probably be best simply due to the smaller area the fan has to pull from. If you have enough space above/below depending on orientation, a standard 25mm thick fan will still work.