A friend of mine suggested rice. Another friend tried it, with good results, so I did the same. Plain ol' white rice, though I don't think it much matters. Very inexpensive, as well. If humidity is an issue with this choice, or cat litter, it'll be one only in a more humid climate.
If going with cat litter, make sure it's unscented. If it is scented, your cat/s might take an interest in sniffing around it, and, well, you get the picture.
If going with cat litter, make sure it's unscented. If it is scented, your cat/s might take an interest in sniffing around it, and, well, you get the picture.