Winter glove redesign... ideas wanted

i always liked the idea of these rather than using batterys use a sustainable source of fuel and quite an elegant solution

a pocket on the back of the gloves into which something like this could be slotter

a thought on the warming issue ... if there was one ?

Only problem with that Dicki is that it will only heat one area and means that area will be uncomfortable too...the gloves have elements in each finger and the back of the hand which don't restrict movement.
The current lithium battery packs are only half an inch thick by two inch by two and a half inch so aren't that cumbersome.
They can be recharged too which obviously uses electricity but is better than using disposable batteries.