I have a workable ferret barrier that also doesn't look too terrible.  How
to explain it?
 
Home Depot sells a PVC lattice, the type of thing you put under a deck or
porch to block the view under the house.  The PVC slides into a special
molding, also white plastic, that is about 1 inch by 2 inches and has a deep
groove in it.  An 8 foot piece of this molding costs about $4.  I cut two
2-ft pieces of this molding and screw it into each side of the door frame I
wish to block.  It doesn't have to be flush to the floor if there is a
saddle.  The two pieces then form a slot in which to slide in a removable
panel.  Although the molding looks like you can't screw it into the wood, I
used long sheetrock screws and an electric drill.  The head of the screw
pushed the groove apart and then countersunk itself into the doorframe.  The
panel is thin white melamine, the type of cheap paneling used in bathrooms.
Cut the panel to fit the space, in my case, just under 30".  I cut it 25"
high, which so far is high enough to deter leaping weasels but low enough
for poor old mom (me) to clamber over.  It's also very slippery.  The
paneling and the molding cuts easily with a saber saw.  The whole thing
looks clean and white and not too bad when company's coming!  It's also easy
to lift in and out whenever you want.
 
Happy barricading!
 
Kat
[Posted in FML issue 2316]