In last weeks FML someone wrote that they attached molding to the doorway in
order to slide in a board to keep the ferret in the room.
I suggest an easier and less destructive method:  Get a piece of plexi-glass
about 3 feet by 4 feet (depending on the size of your doorway).  The
plexi-glass should "bend" to fit in the doorway and be high enough that the
ferret can't reach the top (please note that they can jump a few inches high).
The force  of the plexi-glass against the doorway will keep it in place thus
confining the carpet shark to that room.  Ferret dancing forever, captive
ferrets never.
[Posted in FML issue 1154]