since the fan mount has resonated with the fan vibration and was very loud, i went back two steps. Currently i'm using:
this is a remix from:
Cover / 70mm Fan Mount for Geeetech GT2560 by esurplusplus https://www.thingiverse.com/thing:1810089
i like the design of the open cover!
that way, my cable management is not limited into small holes somewhere i don't need them.
i basically just converted the original (for 70mm fan) file into a cover for a 40mm fan.
(original files included and untouched)
======== Original Summary ==========
Simple cover / 70mm fan mount for a Geeetech GT2560 contoller board. Includes a standoff for the back side of the board. I secured mine by gluing in M3 threaded rods (M3 screws with the heads cut off) into the cover (long enough to go through the board/standoff/and printer frame) and M3 nuts.