I just made my own hand warmer out of an old t-shirt and some instant rice (I know, I'm supposed to use uncooked, but it's all we had!). My question is, what else holds heat well that I could use besides rice? We have some dried beans (pintos, etc.) in the pantry. Would those work? Nothing beats the feel of rice in these things, but we do eat quite a bit of rice....so we kind of need it...haha Thanks!