Some of the best money I spent was on this hot/cold water bottle from the drug store. As soon as the temperatures start dropping, I have cold feet until Spring warms them up again. It is so bad that I cannot fall asleep if my feet are cold so I put a water bottle filled with hot tap water at the foot of my bed to keep my toes toasty! I think I would like to make a cover for mine, but given my list of projects it might be a while!