Plate with ducting to allow the use of 40x40x10mm fans (like the Noctua ones in the photo) for a quieter experience.
The step file is available if you wish to edit it for tolerances or to use heatset inserts, for example.
By default, the holes are designed to be used with M3 screws of variable height depending on fan thickness.
The author remixed this model.
allow for non radial fans for a quieter experience.