This is a remix of the "Prusa XL Buddy cover", which fits an 80x80 fan and a DC barrel jack.
The fan can be mounted with four screws with countersunk heads (M4x14 or more) and nuts.
The original Buddy cover screws should be replaced with longer ones (M3x12) as the rear side is thicker.
If you are using a 24 volt fan, you can power it directly from the XL board.
The author remixed this model.
Bigger fan (80x80) with hole for DC barrel jack adapter.