Tutorial: Color-swirled cupcakes

I helped with a friend's baby shower last month and it was my job to make the cake. I was SO excited, because the theme was "The Very Hungry Caterpillar" book by Eric Carle. I'd seen a few cakes online that inspired me, so I had lots of ideas. I wanted to try color-swirling my cupcakes so my caterpillar would resemble the one in the book, but I had never tried this technique before. Here are 3 options for multi-colored frosting:

1. Brush striping (for bold color stripes): Put the tip onto your pastry bag, then fold the edges down. Squeeze or brush food coloring in stripes from the pastry tip out toward the wide end of the bag. Carefully spoon frosting into the bag, then decorate cupcakes.   
2. Spatula Striping (for subtle color swirls): Make 2 (or more) different colors of frosting. Using a spatula, layer different colors of frosting into your pastry bag, then swirl onto cupcakes.
3. Separate color swirl technique: Make 2 different colors of frosting. Lay out a rectangle of waxed paper, then spread your first color onto it in a long stripe. Roll it up and twist one end. Repeat with the other color of frosting. Cut one end of each frosting roll and place side by side in a prepared pastry bag. When you squeeze the frosting out, it will have 2 colors, side by side! HERE's a great tutorial for this technique.

TIPS: You'll do best with a thicker frosting, such as buttercream. When you are ready to decorate your cupcakes, squeeze all the air out and get the frosting flowing first by testing on a plate.

For this cake, I used 1 box of Devil's Food cake and made 22 cupcakes and baked the small round cake (for the caterpillar's head) in a Pyrex glass bowl. I made the eyes, nose, feet and antennae out of Marzipan (almond paste) that I colored with food coloring. I covered a large piece of cardboard with wrapping paper for the backdrop. 

UPDATE: July, 2011: 

I used technique #3 (3 separate colors, wrapped in waxed paper, then put in one pastry bag) for my daughter's birthday party and here's how the cupcakes turned out...