Hot Wire Cutter
From DT Online
Hot Wire Cutters comprise a thin wire which becomes hot enough to cut through some plastic foams once a small low voltage electric current is passed through. The wire is usually nichrome resistance wire.
They are useful for cutting expanded polystyrene and Styrofoam for model making or lost foam casting
Safety Point! The wire becomes hot in use and fumes from melting plastic may be harmful so should be avoided. Use Hot Wire Cutters sparingly in well ventillated conditions.
Hot Wire Cutters can be made using thin guitar strings or perhaps fuse wire. Lantern batteries may provide a power source but experimentation is needed with regard to the wire length. A means of varying the voltage and some knowledge of Ohm's Law is also useful.
Safety Point! NEVER experiment with mains electricity - this can kill!