This is a lot of fun to do with the kids. Make any good sugar cookie dough. I use the Rich Roll Cookies from The Joy of Cooking. I NEVER refrigerate the dough before I roll it out. I refrigerate it AFTER.
After mixing the dough, roll out a large handful between 2 sheets of plastic wrap. Lay the rolled-out cookie dough on a baking sheet, sheet pan or tray. Continue with rest of dough, layering each sheet with plastic between each layer. Freeze for 10 minutes or refrigerate for 20 to 30 minutes. (You can wrap the layers airtight and freeze for up to a month.) Remove sheets of dough from freezer or fridge. Cut out cookies. (It's a breeze when the dough is nice and cold.) Place on foil-lined and Pam-ed baking sheet.
To decorate, I use egg yolk paint. Separate 3 yolks into three separate bowls, saving the whites for something else. (They can be frozen, well-sealed, and thawed and used for meringues. One egg white equals 2 tablespoons or 1 ounce. Four egg whites would be half a cup.)
Add 1 teaspoon of water to each yolk. Leave one bowl as it is, that will be your yellow paint. Add coloring (Wilton paste coloring is good) to the others. I usually color one yolk red and the other green. (Blue is a bit problematical, when you're starting with a yellow yolk.) Using a new paintbrush for each color, paint the UNBAKED cookies with the colored yolk paint. Sprinkle with sugar and or sprinkles. Bake according to recipe, keeping a careful watch.
Now sit back, turn on your speakers and watch someone else do all the work...