I had fun adding herbs and spices to them to create lots of smells. Deciding what spices to put in is like cooking. I've made one with lavender, one with a mixture of Indian-inspired spices that reminds us of Indian sweets, another with cumin, black coriander, bay leaves, & pepper, and some other experiments. Or you can leave out the spices if you want to keep it simpler.
There are lots of instructables for neck, hand, and other warmers made from fabric and heatable fillers. I've included mine because I wanted to emphasize how much fun you can have creating a spice mixture, how you can use almost any kind of fabric, and to give detailed sewing instructions for a handy multi-purpose size.
Worn-out sheets and pillowcases are great; you can use any fabric you want. Worn-out things around the house are soft and smooth, such as flannel from nightclothes or knits from old T-shirts. Of course you can use new yard goods. This project shows one made from an old sheet, one from a T-shirt, and one from some soft old towels.
Step 1: Gather Materials
Step 2: Cut and Sew
If you have thicker or stronger fabric, then just use one layer. Cut 12" by 17" and fold once. Or cut two separate pieces about 12" x 8". Remember to put WRONG sides of fabric together before sewing, because the RIGHT sides come to the outside when it is turned inside out.
I have used black thread here for contrast, but you may prefer to use matching thread.
Trim corners and trim edges except along the filler hole.
Turn inside out, pushing out corners with your fingers to form a soft rectangle.
Step 3: Fill With Rice and Spices
Decide on your herbs and spices. This is the fun part. Lavender is classic from many traditions. Or choose whole spices, seeds, and herbs. Or choose pre-ground spices. Use whatever you have at home. You can add them whole, loosely crack them with a hammer or back of a spoon, or crack or grind them in a spice grinder. For this heater I choose Bay Leaves, Black Pepper, Black Cardamom, and Cumin Seeds lightly cracked in a grinder. I put about 2 tablespoons of spices in. I let them mix with the rice as I pour, but you can drop them in later, and mix them by kneading the bag.
Step 4: Finish Sewing
Step 5: Microwave
You can microwave as many times as you want. The rice put out some moisture at first, which is nice, and eventually dries out but still heats.
You can also put these in the freezer for a cool pack, but that's a different contest...
Step 6: Other Fabrics
These pictures show three heaters. Here are the fabrics and spices:
1. Two pieces of old towel with short grain rice, plus diced vanilla bean, pinch ground cinnamon, ground dried ginger.
2. Old sheets, double-thickness fabric, short-grain rice, bay leaves, black cardamom, cumin seeds, black pepper.
3. Front and back of child's outgrown tee-shirt, jasmine rice.