These cupcakes are so much fun and they look a lot harder than they are. We simply used two boxes of white cake mix. We ended up with way more batter than we needed, so we made a cake too. I'm sure you could get away with one box. Once we mixed the batter, we divided it into five bowls and mixed in the food coloring. Then we just made a layer of each color in each cupcake liner.
It does take a long time to layer the colors. The first one we tried ended up overflowing a lot, so we had to do very thin layers, which is what took so long. However, it would be a lot easier if you only use four colors instead of five.
Any frosting will work for these, I know everyone prefers different kinds for their cupcakes. I don't remember what we used for these.
The girls on my floor devoured these before I could get any good pictures of them, so all you get are some awesome cell phone pictures.