Adapter for 120mm fan in 3x5.25" drive bays

I still use some 4U rackmount ATX cases that are a bit over 20 years old.  Due to their age, they only have 2 80mm fan mounts so the airflow is insufficient for most modern processors.   The good news is that they have 3 5.25" drive bays.   Another of my models here will mount 3x40mm fans in a single 5.25" bay - that one is used in another system with a hard drive adapter in the other 2 bays.  The computer for this one had nothing that needed to go in the bays so I measured and found that a 120mm fan would fit comfortably and remixed my other model to use a much bigger fan which can push a lot more air.

I've only printed this with Prusa PC CF blend.  It may need a bit of adjustment for other materials.

My crude OpenSCAD source code is included in case it isn't a perfect fit for your case.