Several years ago when my son was young, we filled one of those hard plastic molded swimming pools full of sand as a sandbox. I let my ferrets dig in this, they loved it. There was no walls to dig under, the sand was soft enough (and cleaner than dirt) but if you get it a little wet, it molds and keeps a tunnel formed when they dig. This is a great way to let them dig, stay cleaner, yet can be used over and over, without ruining your lawn. Cathy [Posted in FML issue 1586]