140mm Case Fan Holder / Radiator Booster

I almost bought a radiator booster but those things usually have very small fans to fit into the radiator. In general small fans need high rpm to move a decent amount of air and I didn't want to gamble on fan-noise.

As I have some spare 140mm computer case fans that can be run totally silent when restricted to ~600rpm (and if nothing is partially blocking the fan), I decided to design a simple raiser that will lift the fan a few centimeter under my radiator.

Using 140mm fans is bulky and som of the airflow might be less effective, as the fans are bigger than the depth of my radiator, but I don't care about that (I simply wanted to use the silent fans, that I already had lying around).

The riser/holder is 90mm high and the fans are simply put on the little nubs on top (it's a loose fit on purpose).
On two sides, I added 2 holes (2.8mm) for M3 screws. This way multiple holders can be screwed together.

Hole distance of the fan is 125mm which is most common for 140mm case fans.

I recommend to add a print modifier object (cylinder) and place it on all 4 nubs on top and pull them 3-4mm down into the model. Set those modifiers to have one more perimeter, than the global print setting. This way the nubs are way more fused with the print and won't break off as easy as with standard print settings.

I also attached my FreeCAD file (created with v 1.1.0.dev) if you would like to change the height for example.