CircuitSetup provides some variations on the 3D printable case for their 6-channel energy monitor (https://github.com/CircuitSetup/Expandable-6-Channel-ESP32-Energy-Meter/tree/master/Hardware). I liked the 3-part case, but the snap-together mechanism didn't work very well for me. I remixed it by merging the “small” and “large” halves together as a single piece to get past that problem. However, that then makes it almost impossible to insert the PCB. So, I cut away some pieces in PrusaSlicer to take care of that. I also added a solid bar to reinforce where the original seam appears where the two halves join. (There's probably a simple way to modify the original Fusion360 design file for all of that, but I don't know how to do that.)

While I was at it, I added some text engravings for marking the numbers for the CT plugins. My plan is to mount the case lid on a wall and snap the body of the case onto it, so the engravings appear on what is normally the outside bottom of the case. I included a filament change to give contrast to the engraved lettering.

The resulting files uploaded here include a simple STL for the overall resulting shape. There is also a 3MF file that shows the various piece-parts individually. Use the lid STL from the original design.