> Foam constructed bodies would be less prone to have memory while denser
> bodies would be likely to "warp". Also depends on the plastic.

In Canada, Tegart Apiaries have devised a five-frame nuc box that stands up
really well.  The unit costs about $20 US.  It has hard plastic contact and
lid surfaces and is stryo filled.  It is quite similar in some ways to a
good quality picnic cooler.

They have proven extremely durable and stand up for many years of trucking
and bashing around.

allen
http://www.internode.net/HoneyBee/Diary/