That's a bad design. make sure you keep some airflow around the miner, not just the hashboards. The controller above is notorious for breaking from overheat due to people sealing the airflow within the fans while ignoring the rest.

Attach your fan to a larger box, and put the miner freely inside that box. The miner inside should not be in contact with the box or duct. And you might as well leave the PSU in there, just like the newer S15 does anyway. Wood is good, and you could cover the walls inside with sound proofing fabric. Using a bit of sound insulated duct at the ends also helps.

I have seen another design where the air is following little Z like maze before going out. But there is an important design change, the holes are larger and of rectangular shape half covered, not round duct like. The maker describes it as a "nozzle" effect, noise cancelling but air flowing.

I'm actually worried your squirrel fan would make the others move, ie, generate electricity... Which is the same reason people should not let a fan spin when dusting off electronics with an air blower (they will generate and send electricity down the wire possibly damaging things).