The Freebox Pop is quite small and I find its cooling inadequate. I've had internet outages and a very hot box to the touch. I came across RedOhm's excellent work on Grabcad, but I wanted something simpler, so I redesigned everything.

It is necessary to purchase this fan: https://www.amazon.fr/gp/product/B06XQWMFDQ/ref=ppx_yo_dt_b_asin_title_o08_s00?ie=UTF8&psc=1

Procedure:

1. Print the bottom part, drawing the supports under the fan's mounting tabs (to avoid having supports everywhere)
2. Print the top part, 0.3mm fill 10% works
3. Disassemble the fan's 2 grilles and keep the screws
4. Place the fan on top of the tabs and secure it from below (you can use the gap between the fan's casing and the base to place the cable)
5. Choose your fan speed, connect it to the USB port and place the box

So yes, the assembly uses the only available USB port to connect an external hard drive, perhaps try a USB splitter if you need to connect an external hard drive.

On the graph below you can see the temperature dropping as soon as I installed the box on the cooler with the fan at minimum speed.