When I had leopard geckos, I used pea gravel. It's something they never tried to eat or lick - even when chasing crickets. The calcium sand gives them a reason to try to consume it, which can lead to impaction - even if it's just an accident. You could just use paper towels because it's by far the easiest for lizards like beardies who don't necessarily burrow. Not to mention easy to clean/replace I find pea gravel makes a great all-around substrate for beardies and certain geckos. It's very cheap, too. And as an added bonus: it looks great.