I make my own ferret "gates" by going to Lowe's (or somewhere similar) and
have them cut me a piece of Plexiglas about 24-30" high (depends on how
high your fuzzies can jump) and about 45-60" wide (roughly 1 1/2 times your
door width).  Then I simply brace it on either side of the door by bending
the Plexiglas to fit.  This DOESN'T work unless you have a baseboard or
corner type niche to catch the plexi as the ferrets can work it loose
otherwise.  I also use it in hallways to block access by fuzzies to certain
areas of the house.
 
The cost is usually around $15, much cheaper than a lot of alternatives.
 
Karla
Meep and Daisy
[Posted in FML issue 2926]