We purchased one of the Ferret Playpens and haven't had any problems with
escapees.  We got it to use when we traveled and stayed in hotels as it
gives plenty of space to play, yet keeps the fuzzies contained so they
won't come to any harm---such as crawling into the bedsprings, finding
an escape hole or possibly coming across something that may have been
dropped by previous residents and not cleaned/picked up such as medicines
or other hazards.
 
One thing to keep in mind when using it is not to have anything that
they can use as a "ladder" to get over the sides.  We either set their
travel carrier in the middle or after laying a sheet down, would put the
contents of the carrier---sleep covers, littler box, toys, food/water
etc.  out within the pen.  They enjoyed the freedom and we had a lot
easier time keeping track of them after a long day of traveling!
 
All the best to fuzzies everywhere
[Posted in FML issue 4108]