Homemade Hot Wire Foam Cutter

Updated April 17, 2017

A hot wire foam cutter is a tool used to cut polystyrene foam, foam insulation boards and similar materials. The tool generally consists of a special metal wire bent into the desired shape then heated enough to vaporise and cut through foam. There are various types of hot wire foam cutters available at a variety of prices. A less costly alternative is to build your own hot wire foam cutter with commonly available parts found at most hardware stores.

Strip 2 centimetres of insulation off both ends of the 40-inch insulated copper wire.

Measure 15 centimetres from each end of the copper wire and make a mark with a marker.

Use the wire strippers to strip the 10 inches of insulation between the two marks. Cut away the outer pieces of copper wire from the stripped centre of the wire with wire cutters. Leave the centre strand intact.

Bend the wire at the edges of the stripped centre so the stripped centre remains straight. The wire should form a less-rounded "U" shape, where the bare wire will be used to cut foam.

Measure 9 centimetres from the edges of the stripped centre on each of the "U" arms with a ruler. Bend the two arms of the "U" shape inward at the 9 centimetre mark.

Measure 3 centimetres from the previous bend. Bend the two wires outward from the 3 centimetre mark.

Loosen the screws in the soldering gun's terminal post to remove the wire that comes attached to the soldering gun. Remove the wire by gently pulling it out.

Insert the stripped ends of the copper wire into the gun's terminal posts. Tighten the screws to secure the wire.

Plug the soldering gun in. Allow the wire to heat up and use the bare portion of the copper wire to cut foam as desired.


Bend the centre uninsulated portion of the copper wire into different shapes to make customised cuts into the foam. Use the cutter to cut polystyrene foam such as the popular styrofoam. Other materials including polyurethane foams will give off toxic fumes if cut.


Always use caution when handling a soldering gun, especially with the new hot wire cutter attached to the gun. Make sure to wear gloves for protection against potential hazards.

Things You'll Need

  • 40-inch insulated copper wire
  • Wire strippers
  • Ruler
  • Marker
  • Wire cutters
  • Screwdriver
  • 100-watt soldering gun
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About the Author

Scarlett Gauthier began writing in 2003. Gauthier has a graphic design/arts DVS from Rosemount Technology Center in Montreal.