Arvo KD9XLC has put one of these 12v fans that cost less than a dollar on the back of his Excelway case from Bangood (which apparently now on sale for $8.88).
You could attach the fan to the cabinet with hot glue, or use the correctly sized bolts/nuts.
And if you don’t want those fans to run on receive connect them to the TX 12v line, namely at pin 3 on U2, which is what Arvo did.
