Nichrome wire has a resistance of about 1 – 2 ohms per foot for a 0.6 – 0.4mm wire, so that piece there may easily draw 10 amps out of the battery and not all cells are designed for that.

The bow-style cutter features laser cut parts, a pair of 1/4-20 bolts, a power supply, and about a foot of nichrome wire. It’s the bare minimum for cutting foam, but it seems to work really ...