GMKtec NucBox K12 Custom Case

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.