I made this for my Libre Computer Le Potato, but I used a model of a Raspberry Pi 3 to make this so they should work also. The buck converter I used is a XY-3606, I like this one since it has both a USB and screw terminal outputs so it was easy to power the board and a 5v fan. The case uses 2 40mm 5v fans, after doing this and adding both fans I realized that 1 was probably sufficient, the Libre Computer doesn't need active cooling at all and the only thing that may need cooling would be the buck converter. I use Klipper and a ADXL for Input Shaper so I attempted to make my own dupont connector and housing so I'm able to to plug up the ADXL easily when needed. That seems to be working fine for me so far. I used 3D models of an Ender 3 Pro, a Raspberry Pi 3, and a 40mm fan to help get everything to fit well enough to work. Here is the link to the models I used:

40mm Fan:

    Model: https://grabcad.com/library/40mm-dc-fan-1

    Author: https://grabcad.com/aronsta-1

Raspberry Pi:

    Model: https://www.thingiverse.com/thing:2863567

    Author: https://www.thingiverse.com/keepars/designs

Ender 3 Pro:

    Model: https://github.com/hyotynen/Ender-3-Pro/tree/master/3D%20Model/Ender%203%20Pro%20-%20Stock/STP

    Author: https://github.com/hyotynen

And the Buck Converter: https://www.amazon.com/dp/B07XXWQ49N?psc=1&ref=ppx_yo2ov_dt_b_product_details

Also, the enclosure is slightly below the bottom of the frame so you will need risers. I've included some feet that I threw together but I would suggest finding a different riser since mine don't fit well, they are real loose. I do plan on putting some time in and get them to fit better soon though, or possibly just shorten the enclosure, IDK.

The enclosure uses 4 M3 screws with nuts to go with them, on the body of the enclosure there are holes where I used a couple drops of super glue to fasten the M3 nuts and that holds the lid on, right now until I think of a better way the USB from the computer to the printer just fits through a slot in the lid. The fans are also just held in with some M3 screws and nuts.

I used a XT60 splitter to power the XY-3606 buck converter. For powering the Raspberry Pi(or whatever SBC) I used the USB output from the XY-3606 and the screw terminals to power one of the fans, I powered the other fan from the Pi. You could also just power both fans from the XY-3606, its up to you really. I also used a label maker to make labels for the inside of the lid for the wire colors so I know what wire goes where.

For the ADXL Lid I used a brim with tree supports on. Everything else I tried to make it printable with no supports.

I'm still learning Fusion360, and it seems I learn something new every time I make something. I appreciate any constructive criticism that will help me learn something for next time.