There isn't a July Fourth weekend -- or any weekend for that matter -- that couldn't use one more bathing suit. It takes virtually no more room in the suitcase, and could double as a top with long cotton skirt or shorts. Also, it could save you from having to climb into a suit still clammy from the day before.

Ann Person, the innovative head of Stretch and Sew (who a few years ago concocted a 7-minute dress) has come up with what she calls a 3-minute swimsuit. (The countdown -- which just could be slightly exaggerated -- starts, of course, after you have the materials in hand.)

The materials: One square yard of Lycra/spandex ($6.95 to $18.95 a yard), which is chlorine-resistant; a ballpoint needle (4 for $2.25), and polyester thread. Directions for making are diagrammed below.

And when you have the two triangles joined together, here's how to don (in 3 seconds?): Bring two ends under the arms to the back -- to form the strapless top -- and bring the bottom triangle through the legs and tie ends around waist. Volia !

One word of propriety: If you are a diver, dive gently and come to the surface cautiously. And you may not want to wear the 3-minute suit for a too-strenuous game . . . oops . . . of volleyball on the beach.

Whatever, you'll be sitting pretty. And isn't that what vacations are all about?