I made this simple testing array to combine different colors together and have as a reference for the future when coloring prints. This is to be used with Full Spectrum in Orca Slicer and should generally only be used if you have a tool changer printer like the Snapmaker U1. 

The trays is infinitely expandable if you want and the cylinders should press fit into it no problem. I gave extra clearance for the trays to be able to slip in and out easily though so it is nice and simple to look at what you need.

I usually print the cylinders at .08 mm layer height to get the best color blend.

You can download this version of Orca Slicer here: GitHub - ratdoux/OrcaSlicer-FullSpectrum: G-code generator for Snapmaker U1 with Full Spectrum layer blending · GitHub