Prepare cake mix per package directions. Separate batter into smaller bowls equaling the number of desired colors for the finished cake.

Using food coloring, color each bowl of cake batter your desired shade. Red + Blue = Purple, Blue + Yellow = Green, Yellow + Red = Orange.

Spoon approximately one teaspoon of each color into the center of the cupcake cup (each spoonful will spread the batter out). Repeat for all cupcake cups. 

Using a butter knife, fold the batter in each cup 2 to 3 times, in different directions, to slightly mix the colored layers. Finish up by drawing a "figure 8" in each cup. Do not overmix; the colors should remain distinct.

Bake cupcakes per package directions. Frost and decorate as desired.

Optional: For added interest, add a few drops of fruit extract to each portion of colored batter for a flavored cake. For example, cherry for red, lime for green, orange for orange, etc.