First off: Rice Packs.
Take a soft kitchen towel. Fold it in half. Then sew up all the sides. But leave one small opening so you can add the rice. Once it's stitched put rice in it. Just regular raw rice. Don't add too much or it will be too hard on your body. Just use your own judgment as to how full to make it. It shouldn't be more than 1 pound. Then sew the small opening up. And bingo, you have a rice pack. To use it, do the following.
Hot:
Take the rice pack and place it in a microwave. Zap it for approx. 1 minute. It shouldn't take any longer than that. Make it as warm as you can stand it. Then just place it on your body where it hurts the most. It's great to use on shoulders, hips, lower back, neck, just about anywhere. You can sew on ties to it so you can tie to yourself where you need it.
Cold:
Place the rice pack in the freezer. You can freeze for as long as you want. If cold works better for you, then you can freeze the rice pack and you instantly have a cold pack to place where you need it.