This is as true for insulation board as it is for the ubiquitous expanded polystyrene kind of foam used for everything from coffee cups to packaging material. Those stick-type hot wire cutters ...
What you really need is a hot wire for nice clean cuts. [Elite Worm] built a hot wire foam cutter that can cut any type of foam with ease, be it Styrofoam or grey craft foam. There are a ton of ...