1 cup plaster of paris (do not pack)
 almost 1/2 cup cool water
 Liquid tempera paint in various colors
         (your kid’s teacher may “donate” the paint in exchange for a few
         sticks of chalk)
 Margarine tubs or other disposable mixing containers
 Disposable molds
         (we used toilet paper rolls with tape covering one end to make a
 This stuff won't work on chalkboards, it’s too hard, but it works great
 on sidewalks and lasts MUCH longer than store bought stuff.  I made it
 for christmas presents this year for kids, and it worked great!
 Warning: this is a fun and messy project!
 Pour plaster into a container.  Using a disposable stick, stir in most
 of the water.  Add 2 or 3 tablespoons of liquid tempera, mixing well,
 especially at the bottom.  Add a little more water so the mixture
 thickens, stir well, and pour into the molds.  Remove the molds after
 the chalk is completely dry.
 Source: Amy Dacyczn’s Tightwad Gazette II