Put its thickness at about half an inch. Use the sculpting tools to cut it into a rectangular shape.;
, Press them gently, preferably one at a time, and not overlapping.
 This is best done using a craft knife or other very thin tool so as to not damage the pattern.
 Sometimes the stamp will turn out rounded on the top. If this happens then sand the stamp down until it is even.
 Press fairly hard to ensure a proper stamp into the foam. If your foam is larger than your stamp, rotate the stamp as you continue stamping to vary the rocks. For a more well defined pattern you can trace over the imprint with a pencil, pushing firmly but gently to deepen the cracks but not damage the foam.

Flatten some sculpey on the wax paper.
Use the small rocks to press a pattern into the sculpey.
Gently remove the rocks one at a time.
Put the stamp into the oven, following the directions given on the box.
Press the stamp onto the foam that you're using for your foamcore building.
Paint the foam with a mixture of acrylic paints that gives you the color you desire.
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