How to Carve Foam Blocks
Foam is a lightweight material that's often used to create inexpensive theater props, sculptures or models. Items created by carving foam blocks can be quickly completed, using many of the same methods used in carving wood; and like wood, once carved, the foam can easily be painted for display. While the same tools used in wood carving can be used with carving foam, a commonly carving tool is the hotwire foam cutter, which speeds up the process of rough shape cutting considerably.
Instructions
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Create the foam block you wish to carve your object from. Multiple pieces of foam can be glued together to create a single large block using a water-based foam adhesive. Wait for the adhesive to completely dry according to the manufacturer's instructions before carving.
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2
Sketch the form you wish to carve from the foam using a marker on the surface of the foam. You can sketch the form from multiple angles using all sides of the block for easier carving. Sketches can be done from the profile, top and front view to make the carving easier.
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3
Turn on the hot wire foam cutter, and wait 30 seconds for it to grow hot enough to cut through the foam. To test the temperature, push the wire through a piece of scrap foam. The wire is hot enough when it cuts smoothly and cleanly through the foam without snagging or scorching the material.
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Make the initial carving of the shape of your object, cutting away the foam to create a rough approximation of your chosen shape. Begin by cutting away large scrap areas from the form using the hot wire foam cutter. Place the wire against the edge of the foam and drag it steadily through the foam, making a clean cut wherever the wire touches. Continue to carve the foam to form the desired shape, making cuts with the wire until you have a general representation of your final object. Turn off the wire cutter once the rough shaping is completed.
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5
Continue to sculpt your shape from the foam block using a sharp hobby knife and a wood rasp to create details.
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6
Sand the carved foam to smooth the surface of your object using a 400 grit sandpaper.
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Tips & Warnings
Cutting foam creates noxious fumes, so a well ventilated area is necessary.