Draft stopper filling?

Hi, I found instructions to make a draft stopper for under my door but I've seen several suggestions for what to fill it with: kitty litter, sand, corn, rice, etc. I was curious if any of you have made one of these and what you had filled it with. I'd think sand would be pretty heavy and more likely to leak out, but then I'd wonder about the other materials absorbing dirty winter water or attracting bugs. Any suggestions? Thanks!! Sara