This is an example of how I do “keychain” style prints while minimizing color swaps and maximizing color brightness as well as allowing “double the colors” by changing some of the white sections to black for a light/dark shade of each filament.

Both printed models pictured use only 9 color swaps even though the larger model has 6 colors as two of them are just by blackening the white underneath. (My PETG is pretty opaque so for version with different shades I only did 1 layer (0.2mm) of color to get the shading).

The model structure consists of your typical black bottom plus perimeters. The bottom is 2mm of black and a 1mm perimeter wall for 3mm total thickness. The 1mm thick space inside the perimeters is made up of 0.6mm (3 layers) of white or black and then 0.4mm (2 layers) of your color choices resulting in a minimal amount of color swaps due to minimizing the thickness of the colored area required to still get a bright color because of the white backing.

You can use the .3mf from the “double colors” print profile to test out the two different shades you can get from your filament colors. Or you can import the raw files `white1.stl` `white2.stl` `white3.stl` `white4.stl` along with the black.stl and each of the color files then you would make white1.stl and white3.stl black filament, white2.stl and white4.stl white filament and then make `blue.stl` and `green.stl` the same filament selection and `pink.stl` and `purple.stl` the same filament (different from blue/green) and of course `black.stl` use black filament. This will allow you to see the two shades you'll get.