This recipe courtesy of Williams-Sonoma.
Pastry tips, or tubes, used with pastry bags (also known as piping or icing bags) come in a wealth of shapes and sizes, as do the bags. Many tips are for piping specific decorations, such as rose petals or ruffles. But just a handful of plain and star tips provides a wide variety of decorating possibilities. You can decorate a wide range of cakes with only five tips: 3/8-inch, 1/2-inch and 3/4-inch star, plus 3/8-inch and 1/2-inch plain. Look for pastry tips in cookware and baking-supply stores or through mail-order sources.
Adapted from Williams-Sonoma Collection Series, Cake, by Fran Gage (Simon & Schuster, 2003).