I work outside, and have absolutely no circulation in my hands. And I like hair-brained schemes. So with these things in mind, I thought I might have a crack at making a little rechargeable pocket heater. Unfortunately, I know very very little about actual electrics. But hey, that's what makes hair-brained schemes more interesting isn't it? :P Anyways, I was wondering, how would I go about getting something nice and warm using some rechargeable batteries? I've heard that resistors produce heat as a result of, well, resisting. But I don't know how much? Could one warm one's hands if one made a circuit full of resistors (and maybe a little LED so you know when the batteries are dead or dying)? Would the batteries die too soon for this to be a realistic option? What would you suggest? I'm loath to get one of those annoying heat pack things as I find they only last about half an hour, or get *too* hot (one virtue of an electrical appliance - it has an off button).