Hi pamster,
I would not recommend you do this . . . there is a real risk of burning your feet. It takes expertise and access to the right materials to do this safely. Even if you were to make something that seemed to work in your home, things can go very wrong in actual use, and the results may not be good.
It may not be as fun as making your own, but the price of heated socks or soles is not that bad, and worth the peace of mind to not get second or third degree burns.