On the other side of the question, how about WORST packing material?  I
remember reading somewhere about a person who was promised a large paper
nautilus (Argonauta argo) from someone overseas - in Australia if I remember
correctly.  When it arrived, it was in a wood crate, packed in sand.  It
cost a small fortune in shipping charges, and the shell was, of course,
pulverized.
The shipping container is also important.  A lady once sent me a near world
record size Placopecten magellanicus from Canada.  She packed it in a hat
box (thin cardboard, comparable to a shoebox).  When I picked it up at the
post office, my heart sank - the box, which had been about 10 inches high,
was squashed down to about 4 inches thick, with shreds of paper wrapping and
string hanging off all over the place.  Miraculously, the shell was
undamaged, and now resides in the collection of one of our illustrious
Conch-L'ers.
Or how about no packing material at all!  Many moons ago, when I was a young
but serious collector, an even younger fellow (about 14 I believe) in the
Netherlands contacted me, and offered me a few shells he had collected
locally.  He said he had never traded shells before but would like to - so,
even though he didn't have much to offer, I sent him a small parcel of
common shells, and requested a few things from his short list.  He sent them
to me in a plain white envelope - period!  They weren't even individually
wrapped.  I received a profusly perforated envelope, filled with assorted
fragments that hadn't fallen out through the holes, and - amazingly - one
Epitonium clathrus which made the trip intact!
Paul M.