This is such a fun project, but you will need a couple days from start to finish. First find something to use as a mold, such as a toilet paper tube or a small paper drinking cup. You will also need 1 cup Plaster of Paris, 3/4 cup water, and powdered tempera paint in the color or colors of your choice along with a medium sized bowl and something to stir with. Mix together the Plaster of Paris and the water. Next add the powdered tempera paint and blend well. Let stand for a few minutes to release some of the air bubbles. Then pour the mixture into whatever molds you chose. Set your molds with the mixture aside and let dry completely. Once dry, remove the chalk from the molds and let dry another 24 hours. Now your chalk is ready and you can go outside and have a blast.