Summary:
Trump MAGA-net with no MMU/AMS needed for multiple colors, simply pause on layers to change filament.
Print settings:
PLA, 0.4 nozzle, 0.2 layers, 2 walls, 10% gyroid infill, classic wall, ironing on the topmost surfaces
Magnets:
Designed for four 6x3 magnets. My magnets actual measurement was 6.0mmx2.5mm so the magnet hole is 6.3x2.8. I paused on the top magnet cavity layer and super glued the magnets in before resuming the print.
Filament changes:
Color order for filament changes: white, red, blue
If you stick with 0.2 layer heights:
*Be sure to double check your slicer for layer pauses