hello, one of my projects is to develop some sort of self heating bottle. i must fabricate and build a working prototype. i have a couple of ideas. one is to use the same concept as a toaster. wrap the bottle in nichrome, a type of resistance wire. however, would the wire get hot enough to heat a beverage using maybe 3-4 AA batteries? is there another type of wire that you know of which will work? my other idea is to short 3-4 batteries attached to the bottle. i did some testing and found that this caused the battery to heat up very fast and the battery got very hot. i could be able to attach several double A batteries and short them... i would however would like to run with the wire idea, as it will probably work better, providing that it will work off of a couple of batteries. any input is appreciated, thanks guys.