I've installed two Noctua NF-R8 redux-1200 [80 mm, 9,1 dBA] fans. They are connected to GPIO header (+5V and GND), as I had no required plug to use regular fan socket on the mainboard. As they are requiring 12V there's a small converter : DC-DC Step-Up converter module 5V/8V/9V/12V (https://kamami.pl/en/step-up/580924-dc-dc-step-up-converter-module-5v8v9v12v.html). It converts 5V to 12V and fans are working perfectly fine. Also, as they are super-silent (9dBA only) I dropped the idea to change their speed based on current thermal readings. They are working all the time. Picture attached.

Thanks for sharing such awesome design. I would build the same one too. Would you mind sharing how to build the front panel display? Your picture is showing that the front panel is connecting to GPIO.

Regarding the display. It's cheap 0.96" OLED display connected to GPIO via I2C interface (pins 1, 3, 5 and 9). I couldn't use official OpenMediaVault system because I was not able to activate I2C so I used Armbian and did a small trick to make it working (with device tree overlay). Madness... Of course almost no documentation and useless friendlyelec forum. I'm still not able to make the user button usable :/ Anyway, it is what it is. A NAS :)

M2. For top there are, as far as I remember, 5mm or 6mm long. For front and back panels there are 2mm long.

did you used nuts for them? the holes on the main body are for m3, but the holes for the panels are for m2. :D

Sorry, forgot to mention that. I used this kind of stuff:

Just lack of proper plug :/