I saw this idea of making your own sidewalk chalk a while ago and just got around to trying it. It worked pretty well.
1. We mixed together some Plaster of Paris. I didn't measure anything exactly, and added food coloring.
2. Then we poured it into our mold. I used ice cube trays.
3. We let is sit for about 45 minutes. They popped right out.
4. Then we made some pretty picture on the sidewalk.