This is how I did mine. Not going to dismantle it to show more details.
There are no ventilation holes in the X96Air case so I cut a 3inch round hole in the bottom of the case.
The thing on the bottom is a 4inch fan, which I soldered to the USB 5V,0V pads on the bottom of the circuit board. Runs fairly silent, though in a completely silent room you can just hear it. I used the fan grill to make a stand to keep it from lying flat. I screwed the fan into the four holes on the bottom of the X96Air case - which line up almost perfectly. Unfortunately the USB sockets are powered up all the time - and nothing I tried would get them to go to sleep. Check your fans before use as the first one I tried was much more noisy.
I also dumped the thermal pad (useless) and took the metal plate to make two chunks - one for the SOC and one for the four exposed memory chips. Unfortunately this only catches half of the memory as there is another bank of chips on the other side of the board.
This dropped the idle temp from 76C down to 45C and the SOC temp never goes above 50C under load. I daresay that I could get better cooling if I butchered the case a bit more - but I think it looks quite elegant as it is so didn’t want to compromise the esthetics any more since the new SOC temp is well within spec.
I run my X96Air with dirty regions disabled, performance governor and accelerated graphics. Without the mods it was constantly thermally throttling, now it never throttles.
As a bonus it also cools the two hard drive enclosures it sits on.
Shoog