5.25" drive bay mount for 3x40mm fans

For nearly 25 years, I've been using some old 4U ATX rack mount cases that I got from surplus.  For as long-lived as they've been, the ventilation provided by 2 front-mounted 80mm fans is not enough to run modern CPU/GPU combos without thermal throttling.  I've done a few other minor hacks (and I have some more novel fan ideas in mind) to increase airflow, but they're fairly case-specific (with a case that nearly nobody uses anymore).  This is one of the few that is a bit more universal - in one that currently has a 3 SATA drive caddy sitting in 2 of its 3 5.25" bays, I recently upgraded the CPU and the temperatures have been creeping up.

I've seen some other models to mount 40mm fans in a 5.25" bay, but they seemed either case-specific or required glue.  Maybe I just missed the others - it seems like this wouldn't be too uncommon a model?  Anyway, I whipped this up pretty quickly in OpenSCAD.  I'm not sure that the 5.25" mounting holes are in exactly the right spots since the rails for my case have pretty flexible tolerance.  I designed the rest around Noctua NF-A4x20 PWM fans.  I'm including the source in case it's not a perfect fit for someone else's case and/or fans (or if you want to improve on my super clunky design).
Also, to use the model as-is, you'll need some short M3 heat set inserts - the ones I used were around 3mm tall.  The M3 inserts that I used seemed to work well enough with the 1/8" fans that I'd previously used to mount the rails to another accessory.  YMMV

I don't think that these fans are going to make an enormous difference in the system where they're installed, but maybe they can at least take the edge off of the throttling until I can mess around a bit more with some of my other ideas.