I've remixed this to fit a 40mm fan on top of the Opi - It gets kinda hot during operation so I just glue a heatsink on and add a fan, temperatures drop around 50%.

To mount the fan you need two 15mm PCB spacer.

All holes are made for M3 screws. (I use nylon screws to mount the OPi)

The front plate mount is not edited, you can use the original one. I've added just 3 holes for 3mm LEDs.