There used to be a harness made from rounded nylon, that made a figure 8,
with a metal device in the center (it was packaged on a cardboard cutout
of a ferret).
 
I bought one when I first got my oldest Mikette.  I was letting her
investigate my Mom's backyard.  She was playing around roots and holes of
a large tree.  When her little tail was barely in view I decided she was
to far and went to pull her closer by the harness.  Imagine my horror
when half of the harness came off!  Now I really wanted her out but was
terrified to pull any more on the harness and lose the other half!  I got
her out and quickly got rid of the harness!
 
Since then I've read that the "figure eight harness" is no good, but the
"figure H harnesses" work well.
 
Now I have three fuzzies and three H harnesses.  They are made of a flat
nylon and have two independent circles (one for around the neck one for
around the chest) that are connected by a band section of nylon (thus
forming a kind of H on the ferret)
[Posted in FML issue 3887]