Behold, a Bracket to add a 120mm fan to a PC case, using 3 5.25" drive bays, with a honeycomb grill. The mounting holes for the fan are a bit large; use washers if your screws are small.
I printed at 0.2mm, with no supports and 20% infill…
The author remixed this model.
I basically married the source models together, scaled the honeycomb up a bit so it runs to the edge of the fan, and eliminated two of the side mounts, as redundant, to reduce filament usage.