Those 500 watt halogen worklights throw a lot of heat, and you can get a good tan from it (be careful)
Also , for break time, if you have room, toss an electric blanket on the easy chair in your shop( if you have one) and turn it on. Kinda helps warm the buns.
I have seen battery powered socks, they have been around for years.
I had a hand warmer when I was a Kid. I used to carry it when I went trapping , and sledding .Worked great
Fact is stranger than Fiction