[kayson]

I wonder if you would get good enough results by just extruding two separate filaments simultaneously. Sure, they won't fully mix, but with thin enough layers, you'd benefit from the same visual processing that makes alternating layers look like a solid color...

[jononor]

Dual color filaments exist, and they do not mix at all... It gives the objects a nice transition when rotated. But indicates that color mixing in the nozzle is probably pretty difficult?