So I really want to make this rice heat bag for a friend, but I read about the different fillers one can use and now I'm torn. Apparently, rice doesn't stay hot as long and can scorch, but it's "softer" and can hold scented oils. Cracked corn is easier care, and it retains heat much longer, but I'd imagine it's more "lumpy" and as far as I know, you can't really scent it. :/ Has anyone used one or the other? Help me decide.