All credit to user Curon for the original model.

This case is designed to stand vertically. If you prefer horizontal orientation, use the original model. 

Material: PLA

Case & Stand

Infill:  Gyroid, 15%, layer height 0.2mm.
Inserts: 4x M2 (PCB), 4x M3 (CPU Fan Cover)

Sysfan Cover

Add both models (solid + infill) to your slicer and make sure they are centered. Use Process by Object to modify print settings individually. Ignore Slicer Warning about conflicting G-Code. 

Infill section print settings:

• Layer height: 0.28mm

• Wall loops: 1

• Top/bottom shell layers: 0

• Infill density: 45%

• Infill pattern: Grid

• Fill multiline: 3

• Infill/wall overlap: 30%

You can experiment with different infill patterns (e.g. honeycomb) and density to your liking.

Solid section print settings:

• Layer height: 0.2mm

• Wall loops: 3

• Top shell layers: 4

• Bottom shell layers: 3

• Infill density: 15%

• Infill pattern: Gyroid

• Fill multiline: 1

Inserts: 2x M3 for sidemounts 

CPU Fan Cover

Same print settings as the Sysfan Cover. May need supports for the 4 screw holes. Attach with 4× M3 countersink screws. Ignore Slicer Warning about conflicting G-Code. 

Fan Recommendation

I first tried a Noctua NF-F12 5V PWM but it was too loud and produced rattling noises.

I then tried a 12V fan I already had (0.36A). Running on the 5V PCB fan header it is near-silent at ~1000 RPM, which is enough for cooling.

My recommendation: just use any 12V fan. At 5V they all run quietly and can stay at "max" permanently. In my testing this mod reduced temps by 8–10°C with a noticeable reduction in noise.