I'm making rice bags to heat up in the microwave. If you make just little tubes or whatever, people could put them in their pockets, or make them big enough to put in a bed as a foot warmer or something. I used some flannels I found, and you can individualize them even further by finding a way to scent it with that person's favorite scent. Dried lavender, or cloves, or whatever.
Super quick and easy and CHEAP!!! lol