I've seen many posts on different ferret lists about dig stuff for ferrets.
I tried the dig box stuff that www.theferretstore.com sells.  My ferrets
absolutely love it.  It does melt because it's made out of some kind of
starch, sorry I don't know which one.  My one ferret, Buster, chews on
them and I ran it under water to make sure.  I think you can get it from
packaging places too because my boyfriend's job gets it in some packages
they recieve and he brings the stuff home.  Of course, I always test it
under water first.  I just wanted to say that you might want to try this
and it's not that expensive.  I use a plastic container and just dump the
stuff and some of their toys in there and they have a blast.
 
Alice and her four musketeers
[Posted in FML issue 3524]