All you need to make a plaster cast is kinecti sand or clay. Press stamps or make marks into it and when you are happy with your design, pour the plaster into it. As the plaster sets it will feel cold to the touch. When it is ready to take out of the mold it will be room temperature (about 20 minutes). You can then paint it, apply metal leaf or encaustics to the plaster cast. You can hand sand or use a belt sander to sand the edges if desired.