Step 1: Cut 2 pieces of 100% cotton fabric to measure 6"x14". Any size will do, depending on how large or small you want your heat pack to be. Using 100% cotton fabric is very important as you will be using this in the microwave. Other fabric types can melt and metallics will spark in the microwave! Eek!
Step 2: Sew your two pieces together along 3 sides. I used 1/2" seam allowances and then finished them with zigzag, because I really don't want to be spilling rice if one of my seams comes loose. Be sure to leave one side open so that you can fill your bag with rice.
Step 3: Turn your bag right-side-out and fill about 60% full with rice. I used long-grain rice, which is very inexpensive at the grocery store. You don' want to fill it all the way up because then it will be stiff and not comfy to use. Also, it will be extremely difficult to sew closed if you fill it completely.
Step 4: Turn the raw edge of the open side over 1/4" and then 1/4" again and sew the bag closed. I turned it twice because I wanted to make extra sure no rice would leak out.
Only 4 steps, then you're done!
To use, simply put the bag in the microwave, warm up, and apply to desired area. I heated mine for about 40 seconds, because you want it to be warm, but not so hot that it burns your skin! Also, I'm a highly cautious person and so the first few times I heat this bag, I will watch it like a hawk in the microwave with hand on the door ready to stop it if anything weird starts to happen. This probably isn't necessary, but putting non-food items in the microwave makes me a bit squidgy. I highly recommend that you watch yours closely the first few times as well, just to be safe.
Thanks for reading!