See previous page about my first PC fan based build.
My new fan of choice is the Icegale 140MM Xtra - amazon link https://www.amazon.com/gp/product/B08XLHCPWG/
I recommend sticking with only the 140mm fans, as they put out a lot more air than 120mm
This power supply can drive 4 fans, smaller size ones had major issues (heat, would not spin) https://www.amazon.com/gp/product/B0D78FGVJL
One way to attach fans is with a rubber mount. The icegale is solid where the mounting hole is, so you need something that extends fill thickness unlike other fans. ALSO it is curved, won't sit flush, so you need some foam or other way of sealing around the edges. These worked, and let me remove the fans toollessly from the board, so I could fit 2 CR boxes into a carry-on suitcase. https://www.amazon.com/gp/product/B0C75BRD8T
A variation of a cr box is using a round filter. For this I used an "O" size that is a bit bigger than the 140mm fan. I could go a bit smaller, but could not find something worth taking a risk on on amazon. https://www.amazon.com/gp/product/B0CC1DQPB6
This used a smaller power supply cause it was a single fan. Bit of cardboard and duct tape to attach it. I still have to measure the output.