What you'll need:
Toilet paper or paper towel tubes
Small bucket or disposable container to make the recipe
¾ cup of warm water
1 ½ cups Plaster of Paris
2-3 tablespoons of tempera paint
Step 1: If you are using paper towel tubes, cut each tube in half, so it is roughly the length of a toilet paper roll tube.
Step 2: Cover one end of each tube with duct table to hold the contents within.
Step 3: Cut as many pieces of wax paper as you have tubes. Roughly 6 inches X 6 inches. Roll the wax paper loosely and insert into the tubes so as to effectively line the tubes. The top of the wax paper will be higher than the tubes. The wax paper liner will keep the chalk mixture from sticking to the cardboard tubes and will eventually be peeled off.
Step 4: Pour the warm water into the bucket. Sprinkle the Plaster of Paris over the water and stir the mixture with a plastic spoon. The Plaster of Paris roughly starts hardening within 20-30 minutes, so you need to work fast so that it does not harden too quickly.
Step 5: Next pour the tempera paint into the Plaster of Paris mixture and stir so that it is mixed thoroughly. If you would like brighter colors add more tempera paint into the mixture.
Step 6: Stand each tube with the tape side down on a cookie sheet/flat baking dish/box lid to make the project easier to transport to a drying location. Pour or spoon the colored Plaster of Paris mixture into the wax paper lined tubes. Lightly tap the sides of the tubes to release the air bubbles (so you do not have holes in your chalk). After you have poured the mixture into the tubes start another color. When done trim the excess wax paper so that it is closer to the cardboard tube.
Step 7: Wait for chalk to dry. It may take several days. On the last day, peel off the duct tape so that the underside can dry. When the chalk dries, peel off the paper tubes and wax paper. Your chalk is ready!
Make Sidewalk Chalk