Preheat your oven to 350 degrees. Make sure you wash and dry the inside of each canning jar. Spray the inside of each jar with nonstick cooking spray then set aside.
Scoop 1/2 cups of cake batter into five small bowls. It doesn't have to be perfect, don't panic if you get a little more of less of one color than another. Tint each bowl of cake batter with the food coloring until very bright. (I used a lot of food coloring!) The colors I did were red, blue, purple, yellow and green. But you can use any colors you want!