Things You'll Need
Foam or Styrofoam sheets
Rasp or surform
Foam sanding block
100 grit sandpaper
Foam sheets are a versatile medium that may be used in many craft projects. They are soft but firm enough to make decorations with cookie cutters, painting pictures with acrylic craft paint, sculpting figures and making molds. Foam is a good material for making molds because it cuts easily with a serrated knife, saw or utility knife. You can also carve and sand it for a smooth and clean finish. In a few steps, you can make a mold for almost any object with foam.
Make the foam sanding block by cutting a rectangular block from the foam about 5 inches by 8 inches long and glue 100 grit sandpaper to one side of the block.
Decide what you want to make from your foam mold. If possible, draw the exact dimension of the object on paper.
Use a pencil to mark the measurements of a piece of foam. Add an extra two or three inches to the size of the foam; you want the foam to be slightly larger than the object being molded. Cut the foam along the pencil lines using a utility knife and straight edge. The cut needs to be straight.
Find the center of the foam and mark it with a black marker. Use the template or drawing from step one to trace the dimensions of the object on top of the foam.
Start making cuts or slits along the pencil lines on the sides of the foam line using the utility knife. Use a saw or the utility knife to cut above the pencil lines to remove the excess pieces of foam. You are shaping the foam into the desired form.
Use the surform or rasp to shape any concave areas or curves into the foam. Keep carving until the foam is in the shape of the object.
Smooth any rough spots with the sanding block across the foam mold and dust off any particles. You are ready to mold your object.