A cloth bag of ordinary white rice makes an excellent hot-pad. We make them in all sizes from 5-lb bags that will keep you warm outdoors for an amazing length of time to smaller flat pads with rice-filled channels like roll & tuck upholstery for the face. My sweetie's latest is a drape vest that puts a layer of warm on the back or front as needed. These are great for a sore back, especially in cold weather when ligaments get short and muscles get tight. Almost any cloth will do--we prefer fuzzy cloth, but make them out of anything from velour to denim. Rice bags can be heated in the microwave, by the fire, or in the oven, or in a covered pot on a stove top. Just keep the heat low so nothing gets too hot to touch or bursts into flame. If you get them a little too hot for comfort, just add a few layers of towel. Take a few to a hunting blind, or to a flea-market table in the winter, or to bed on a cold night. Better than a hot brick on cold tootsies. The first few times you warm them up, they'll smell like they cooking rice and provide moist heat. That's just until they get fully dry. Make a few and play with them--you'll get hooked on how nice they feel.