A foam cutter built like a coping saw but held parallel to the wire would offer much better control. [Techgenie]’s handheld hot wire foam cutter is a simple build based on a single 18650 and a ...

[Elite Worm] built a hot wire foam cutter that can cut any type of foam ... but you could go even smaller with a handheld version, or build a larger, CNC-based machine.