Hey
Heres a test model I made up when I had a similar idea.
I warn you though it was an absolute pain in the bananas to do.
My method was to paint the whole mini white then the crevises with thinned out yellow then progress from the yellow outward through my reds then paint all the outer areas black, fix all the lava i messed up about 15 time it takes alot of trial and error to get it right so try it out on another miniature before hand.
Hope this helps.