1 bag of rice and a tube sock makes an instant warmer... I empty the bag of rice into the sock till it's about 1/3 full... tie the end of the sock closed...put in microwave for about 1 min. wrap in towel and put around affected areas. (Be very careful how hot you get your heat sock! Microwaves differ in power and depending on the amount of rice you put in, it may heat faster or slower.) Cheap and re-usable! I also keep one in the freezer as an icepack for sprains and such. It's great the way they conform to the body parts.
Hope this helps some