With a few pieces of homemade chalk, your children can turn the sidewalk into a summer canvas for a colorful mural. Making your own supply of sturdy sticks is easy. Just gather some toilet-tissue tubes, plaster of Paris, powdered tempera paints, and a few craft supplies. Then, follow these steps.

1. Make a mold by covering one end of the tissue tube with duct tape. Loosely roll up a piece of waxed paper and slip it into the tube. This lining will keep the plaster from sticking to the mold.

2. Measure 3/4 cup of warm water into a disposable plastic container. Sprinkle in plaster a little at a time, until the powder no longer dissolves (about twice as much plaster as water). Stir slowly and thoroughly with a spoon. Then, mix in 2 or 3 tablespoons of tempera paint. For pastel shades, combine white tempera with a primary hue. Rinse the spoon under an outdoor faucet or in a jar filled with water to avoid clogging sink drains.

3. Place the mold sealed-end down on a level surface and pour in the wet plaster. Lightly tap the sides of the tube to release air bubbles in the plaster. Let the chalk harden for a couple of days. Then, remove the tape and slide the marking stick out of the mold.