Rainbow Bundt® Cake
Do not use liquid food coloring, as it will change the texture of the cake. Feel free to experiment with different colors, but don't try to do more than 6 as there will not be enough batter for each layer. For a tie-dye effect, use a knife, wooden skewer, or offset spatula to swirl colors. Another option (for a speedier cake) would be to spoon colors sort of randomly in pan. Using this method, you could even create a sort of camouflage effect with various shades of green/brown (chocolate) or red/pink.