I’ve wanted to make one of these for a long time now and I finally found an easy, cheap solution. That plus the motivation of making this as a Christmas gift got me going. I wanted it to be portable and inexpensive but durable and versatile. If I can buy one at the store for $20 then the one I make myself has to be much better and cost less.
The cutting wire is René 41 27AWG. This wire is made of Chromium and Molybdenum instead of the more common Nickle Chromium resistance wire. René wire is stiffer, springier, and doesn’t sag at high temperatures as much as NiChrome.
The power supply is an old AC/DC 12V, 1.5Amp brick I found that has a nice long cord. The supply goes into a brushed speed controller with a servo tester to vary the output power. I tested it on my bench supply and at 12V it draws 1.25 Amps. With the AC/DC brick it draws about 1.1Amps.
I made everything modular with 3mm barrel plugs and .1″ pin header connecters for future improvements. Unfortunately, I had to glue the PVC together in order to make it ridged enough. Oh well.
My initial design had it powered from either wall power or internally rechargeable batteries. Unfortunately I couldn’t find quite the right circuitry so I had to ditch that idea. Here’s the finished product powered up and ready to cut some foam!