This isn't 100% DIY because the cardboard stand is bought, but you do get to dress it up however you like. It's a good balance though if you're busy preparing a lot of things. We found this example of a map themed cupcake tree especially inspiring...It was done with wrapping paper with the map of Italy on it. If you're serving cupcakes at your child's party, instead of buying a stand- or using foam cake plates- you can decorate these tiers however you wish to fit in with a theme or color scheme.
We found the DIY over at Save On Crafts where the cupcake tree is also available for sale.