We've had a sandbox for our ferrets for years now.  Next to the dryer tube,
the sandbox is their favorite.  Like yours, our ferrets love to dig and
make patterns.  Sometimes I hide one of their toys in the sand and they are
quite surprised when they dig it up.  We use a sterilized children's play
sand in a Mr. Turtle wading pool.  Oh we do get some sneezing every once in
a while when the sand gets up their noses, but their ancestors were digging
animals and I figure they are well evolved to handle a little sand up the
nose.
 
Dick B.
4 Li'l Paws Ferret Shelter
[Posted in FML issue 2606]