Quiet MCU shield for Sovol SV06 (Plus) ACE

This is a replacement shield for the MCU box of the Sovol SV06 ACE and SV06 Plus ACE printers. (This model is essentially a companion build to the PSU shield.) While the MCU box is not the worst offender in terms of acoustics (that honor belongs to the PSU), its thermal design is pretty bad. The fan pushes air onto the SoC rather than extracting warm air from the case, and the whole case has too few (and tiny) airholes.

This replaces the MCU shield by one that allows to use an external 80mm fan and (optionally) a 2596 step-down module to reduce the fan's RPM. I would recommend having the new fan pull air out of the case rather than pushing in; this usually makes for a quicker replacement of the air in the case and thus better heat transport. The model file prints fine with 0.2mm line height and a standard 0.4mm nozzle. It will need at least some supports under the cable guides and the upper step-down mount (I recommend organic tree supports). If you plan on printing this on an SV06 ACE or Plus ACE, check your printer profile if (external) thick bridges are enabled, and if so: disable them. (The feature makes overhangs worse in my opinion, and definitely doesn't mix with overhang interfaces over supports.)

What you will need for the build:

1. The printed MCU shield (I recommend using PETG, though PLA should be fine).
2. 1 M4x5 melt-in nut for the door latch.
3. 2 M4x5 melt-in nuts for the fan.
4. 2 M4x35 screws for the fan (I recommend brass, but other materials should be fine).
5. A quiet 8025-type PC case fan of appropriate voltage (24V or 12V when using the step-down module).
6. A simple 80mm fan grill; I used this one.
7. 2 M3x4 melt-in nuts for the step-down module (optional).
8. 2 M3x5 screws for the step-down module (optional).
9. 1 LM2596-type step-down converter module (optional).

Also, if you do not want to damage the existing case shield and fan, you'll need a cable with a JST-XH (2.5mm) plug.  If you want to use the LM2596 module and a ready-made cable with a JST connector: take care of the polarity, as this is not standardised, and that small buck module will fail in a rather melodramatic (and permanent) fashion if you connect it to -24V.

This 3D model is based on the original MCU cover for the SV06 ACE as provided in the STEP data published by Sovol. I removed the x-shaped adornment on the door, added a lot more (and significantly bigger) air holes, and added an opening for an external 80mm fan, as well as supports for an optional 2596-type step-down module.