You may have seen instructions for making sidewalk chalk from plaster of Paris and tempera paint elsewhere. This is an update of that old classic which includes differently colored scraps of chalk for added interest and (in some cases) a touch of grossness.

This is a good way to use up pieces of chalk that have broken or are otherwise too small to use.

Supplies

• Cardboard toilet paper tubes
• Duct tape
• 2 cups plaster of Paris
• 2 cups water
• 2-3 tbsp wet or dry tempera paint
• Waxed paper or newspaper to protect work surface
• Old or disposable container for mixing
• Old or disposable spoon for mixing
• Scrap chalk pieces

Instructions

Prepare old chalk
Wash off the bits of used chalk with water to remove any loose dust or dirt. If desired, slice the chunks of used chalk into smaller pieces. Set them aside on a paper towel.

Prepare molds
Cover one end of each toilet paper tube with duct tape. Place the tubes upright on waxed paper atop a layer of newspaper.

Prepare chalk mixture
Mix plaster of Paris and water, then add paint until you achieve the desired color. Set the mixture aside for two or three minutes.

Fill molds
Place a spoonful of the mixture in the bottom of one tube, then drop in a piece of scrap chalk. Spoon on a bit more mixture to cover the scrap, making sure to eliminate air bubbles. Continue in this manner until the tube is filled. Smooth out the top.

Cleanup
If your mixing utensils are to be kept, wash them outside. Plaster of Paris can clog your plumbing!

Remove molds
Leave the molds standing until the chalk mixture is firm, then peel off the molds. Allow the chalk to air dry another 2 hours, until it is no longer moist.