When we had fireplaces we used a screen made from metal mesh that curved in
at the top and sides.  We bought a size that was larger than you would
normally get for the size of fireplace.  This meant that it more than
covered the opening and because of the curved edges it did not sit right up
against the opening (although the sides touched the wall all around and
left no gaps) and therefore did not get very hot.  I still see these
screens in shops.  What we did next to secure it may not work for everyone
especially if you have decorative woodwork, etc.  around the fireplace that
you don't want to drill into.  We screwed nice looking hooks into the
wall or woodwork on either side and then fastened the screen to them with
something like copper wire.  You could also use a matching set of hooks and
eyes or various other combinations by fastening half to the mesh instead of
using wire.  The ferrets could not budge this, but we could easily unwind
the wire for access to the fireplace.  Be aware that these screens will not
keep the ferrets out without some fastening device and could easily tump
over.  If you have brick or somesuch around your fireplace you could still
drill and attach a hook.  The farts would sometimes climb the mesh but
didn't get burned and couldn't reach our mantel.  Although to be doubly
safe we would refrain from letting them run around when we had a fire
unless we could stay in the room with them and supervise.
 
Shelly
(Who is happy to be safe and dry after - I kid you not - 15 to 20 inches
of rain in one day in the San Antonio and TX Hill Country area with more
to come. Many others are not so lucky.)
[Posted in FML issue 2466]