For every Miner: Two nearly 150mm holes for inlet and two for outlet so the hot air can move out.
Thanks for your answers
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I was not sure if it would be better to remove the plates to have more space for noice reducing foam and stack the miners on their own weight. The problem is that the spacers would cover the inlet and exhaust holes a bit.
In every case i would drill the holes in every miners hight. So the air can flow freely.
If you have any more questions let me know it.
Thank you alot guys