i made regular white cake mix, then separated it into six different bowls. i then did the colors with food coloring (LOTS of food coloring XD) and just dropped a spoon full of each color into cupcake liners. i did it in layers of either red, orange, yellow, green, blue, purple or the other way around. you dont mix them or anything, and just bake them lol.
om nom nom, man, this looks s0o0o00o good! i did this when i was in high school (made a rainbow marble cake using colours instead of like chocolates) and no-one wanted to eat it wif me i'd like some of urs please