It’s not like you can hold the other end to keep it steady. A foam cutter built like a coping saw but held parallel to the wire would offer much better control. [Techgenie]’s handheld hot wire ...

While there are all sorts of ways to build a hot wire foam cutter, this design from [jasonwinfieldnz] is both interesting and imitable. If you don’t already know it, nichrome wire is nifty stuff ...