Several years ago we covered how you can make a DIY heating pad by sewing a pocket out of an old t-shirt and adding dried beans and/or rice. If you need a heat pad in a hurry, you can get the same effect by putting dried beans or rice in a clean sock or pillowcase.
Photo by Linda
Cool Tools notes you should tie the sock or pillow so the rice or beans can't escape, and microwaving for two minutes for up to 10 minutes of heat. After several uses as a heat pad the rice will start to break down, so you may want to retire the rice after a few days of heavy use. You can also experiment with spices and herbs to add in elements of aromatherapy as well.
Homemade Hot Pad [Cool Tools]