This fan bracket was made to add active cooling to the TMC2208 drivers in my FT-6 printer. I'm sure that it could be used in many other applications. I used 6-32 1 1/2" countersunk machine screws to bolt the fans to the bracket with nylon locking nuts and then M5 hardware to thread it into the ACM boards of my machine. You can use thumb screws for easy removal.
If it is not already posted when you read this, I am working on a set of custom top and side covers for the FT-6 for use with these fans. This will not work with the original Pi mounting solution from Folgertech. Lucky you! I have a Pi bracket for mounting the board under the machine on the 2040 extrusion in my design catalog.