With candy molds you get many different objects in one mold that costs less than a single mold by the plaster of Paris. So look around the craft store for things that can be used as molds. I found plastic molds to work the best.
Parental supervision is recommended.
This project is rated EASY to do. It Mix Plaster of Paris and pour into candy molds. The smaller the candy mold the better. If the molds make too large of an object then the weight of the object will take many magnets to keep it from sliding off the refrigerator. Plaster of Paris dries faster the hotter the weather.