Just found the following article that could work with Flux to generate colorful prints once the Software Team provide us mid-stream manual filament change option with layer indication in the Monitor window.
I’ll play the devil’s advocate, I also found this article! Mazuir Ross • Terrible Idea: Coloring Filament with Sharpies
However, I still think it is an interesting idea to try out sometime, maybe with an older, simpler Arduino based printer…