Filament advice, 3mf advice

I’ve only used stl files up to now. I can see that the 3mf files contain more info, including painting for multifilament (ahh, is that what the “mf” means in the file extension?)

I want to use the painting, but with different colours and I can’t seem to change them…are they locked somehow?

And what green would people recommend for a good Cthulhu? I realise this is a matter of taste; Id go for something very dark normally - but all the dark greens seem to be carbon fibre reinforced. Creality’s Dark Green CF is a wonderful colour and would be highlighted very nicely with the glow in the dark green i intend to thread through the model (I’m going for subtle…printing in all glow in the dark just turns your model into a featureless blob)…but I don’t need the carbon fibre, don’t want to put it through my two day old machine (I’ve seen what it does to nozzles) and I don’t particularly want to pay the eye watering price. Suggestions?

For more reference, this is my favourite Cthulhu image…definitely darker than some of the bright bilious greens you sometimes see him painted in;