Mounting plate I modelled in Blender to attach a 60mm exhaust fan to my DIY enclosure. Designed to be sealed after install with silicone, and not obstruct the fan opening at all.
Holes are sized the same as my application fan, fitting the standard PC fan mounting screws.
I printed it in ABS for high temperature printing, though you could also use PETG for similar temperature tolerance. You could also likely get away with a PLA print for low temperature enclosures.
The author marked this model as their own original creation.