Cutting foam is pretty tricky without a hot wire cutter. Don’t have one? Well, lucky for you, [Darcy Whyte] has a guide on how to make one. It takes just over an hour to build, and it costs next to nothing in supplies!
[Darcy] is using an old 9V power wart that he had lying around, but you can probably use any DC power supply. He designed the frame in SketchUp and cut it out with his CNC router, although a saw will work just as well for MDF. A piece of 40 gauge nickel chromium wire was strung taught between two 1/4-20 bolts, with one held back by a spring. The spring acts as a safeguard to prevent snapping the wire during overly aggressive cuts. This may be a simple build, but it does produce a handy tool.
[Darcy] demonstrates cutting foam with his creation in a video after the break. We think he could cut thin plastic with it as well—modify your 3D prints, anyone?—though he may need to crank up the voltage a bit.