Here is my hot wire foam cutter that I made using some scrap wood, an old guitar string, an old 13.8 volt power supply, and an automotive light bulb. Just for clarification, the bulb is a 7506 LL bulb from autozone that I had bought a long time ago and never used. It has .6 ohms resistance according to my multimeter. Since this video, I have added a toggle switch on top for convenience, and I tried using two bulbs hooked up parallel, but the guitar string got way too hot, so I took the second bulb off. It is a very simple design and works pretty good. It’s not the fastest, but it works.