The full description can be found in the linked YouTube video :)

You can find the code, CAD files, KiCad filesand BOM's all in the same repository.

Here is the short version: The result of my idea is a system with three main assemblys:

FAN Stage:

• Using the shroud increases the wind speed by around 80%, which means the device can be placed a bit further away while still staying effective. Check it out in the linked YouTube video! :)
• In addition, the interface_V1 PCBA is installed on the side. The PC fan can be connected to this board, which then passes on the fan’s signals.

Main Electronics Module:

• The electronics module provides approximately 10 W of power. When using
  fans such as the Noctua NF-A12x25 PWM chromax.black.swap, as I do, up to five fan stages can be operated simultaneously.
  

• The Arduino Nano was just the right choice for this project – it’s compact and super easy to work with thanks to the Arduino IDE. Plus, using an Arduino makes it way easier for others to recreate the build, especially if you’ve played around with Arduinos before. The Nano sits on a small custom PCB to hook up a few extra parts – like some LEDs, a DC-DC converter, and one or two other small parts. But don’t worry: the number of components is totally manageable. So go ahead and give it a shot!
  

Tripod:

The goal was to develop, among other things, a modular system. Therefore, the three assemblys can be assembled in various configurations. Here are the setups shown in the YouTube video:

Full Build (with 3/5 Fans)

Desk Setup

Split Mode (Left and Right → Stereo)