Magic Bags are a brand of small cotton sacks filled with a material that can easily be warmed or cooled. It can then be used as a therapeutic tool to relax tense muscles or reduce swelling, similar to a gentle ice pack. It's kind of like a hot water bottle, but it conforms to your body and never leaks. Every household should have one on hand, as they are quite easy to make.
Cut a piece of 100 percent cotton fabric into a rectangle about 14 inches wide and 20 inches long. Soft fabrics like cotton flannel or old sheets are good choices. An old T-shirt can also work.
Fold the piece of cotton in half length-wise. Then sew one short side and one long side together to make a rectangle approximately 7 inches wide by 20 inches long. Leave one end open for stuffing.
Turn the bag inside out and carefully pour the uncooked rice and herbs into the bag. Then fold under the raw edges of the open end and stitch it closed using small, close hand stitches. Make sure your stitches are close enough together that the rice can't get out.
Put the rice-filled bag in the microwave for one to three minutes. Be sure that the bag is in the middle of the turn table so that it heats uniformly. Remove the bag and wrap it around your neck or shoulders. Relax in a chair or on a bed and let the heat penetrate your tense muscles.
Freeze the bag in the freezer for about fifteen minutes to create a cold pack for use on sprains or swollen body parts. It's milder than ice, yet creates the same soothing effect.