Migrating from thingiverse
https://www.thingiverse.com/thing:3807931
remix to fit a 40X40X20mm fan
https://www.thingiverse.com/thing:3399705
the 2 mount screws for the fan are threaded M3 holes, but printing with a resolution of 0.2, the thread are still rough and still need a bit of force the first time around, although a bit easier.
FreeCad design file included
The author hasn't provided the model origin yet.