If you just want to make small adjustments and generate your own version, install openscad, and open a scad file and press F6 to generate. Export->stl to get printable model.

For the top parts, I recommend rotating them 180 degrees in the slicer, so the top is on the printer bed. I used 100% infill, since its not that much difference in time/weight, and I hope that it contributes to a more compact and better sounding case...

Recipe for re-making this

Export board outline from kicad
Open in inkscape, select all and combine
For every point: mark(there will be 2) and select "join points": shft+L(shft L
Import in openscad
Export holes from kicad as svg
Create cutouts, and measure position from kicad
Import holes, just to check that positions match
Comment out holes, generate with F6 and export as stl
Import stl files in any slicer to print them