I love these microwaveable heating pads. The are great for soothing sore muscles, injuries and cramps, or just for warming up your bed before you go to sleep. They are really easy and inexpensive to make and make great gifts!
Step 1: Picking fabric
I use polar fleece for one side and cotton on the other side. The fleece is thicker so that side of the heating pad is not as warm to the touch as the cotton side, which is nice, especially when it just comes out of the microwave and the cotton side might be a bit too hot for a few minutes. Make sure the fabrics don't have any printed designs on them that have glitter or metallic paint. I usually buy fabric in the remnants bin for these because you don't need really big pieces.
For this one, I used some pretty blue cotton and tan fleece. Make sure you wash the fabric first!