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Preschoolers have a knack for getting dirty -- so why fight it?

Get the birthday boy to paint with abandon on card stock then cut into postcard invites. Rubber- stamped office labels wrap around the sides and highlight the theme.

The day before, make batches of play dough for the favors (how-to below). At the party, give each kid a tray with premeasured play-dough ingredients, cookie cutters, and a rolling pin, then tie on kid-size aprons and let them mix some up themselves.

Play Dough How-To
Ingredients
1 cup flour
1/2 cup salt
3 tablespoons vegetable oil
1/3 cup water tinted with 17 drops of food coloring

1. Pour flour, salt, and vegetable oil into a medium bowl, and stir with a wooden spoon.

2. Add colored water, and knead dough with hands until it feels smooth. If the dough is crumbly, add more oil; if it's sticky, add more flour.

3. Dough can be stored in an airtight container in the refrigerator for up to two weeks.

Messy Party Food
Later, guests dig into ooey-gooey banana-split cake made with alternating layers of vanilla cake, vanilla pudding, whipped cream, bananas sliced lengthwise, and chocolate syrup.