Hello, I would like to be able to heat a nichrome wire with batteries (probably with a D batterie, but if it can be done with AA batteries, it's better, cause it's cheaper). I would like to be able to heat a nichrome wire of about 2 feat long at a temperature similar to the body temperature (99F or 37C) for at least 2 hours. For the nichrome wire, thinner is better (more flexible). Eventually I will try to put this in my winter boots and see if it can keep my feet warm. I know heating socks already exist, but I want to try to build my own. So: - what specs should my nichrome wire have - what would be the best batterie for this, and how many do I need - what should I change to keep the same wire temperature, if I change the length of the my wire to 1 foot or 3 feet. Hope I being clear. Thank you.