The superior enterprises boxes worked fine for me.
In general their biggest concern is the animal escaping. So using a foam insulated box, taping appropriately/liberally, filler inside the box, and a snake bag/deli cup to contain the animal that is properly closed/sealed is really all you need.
Adding hot/cold packs (for the test box) isn't necessary as I don't believe that Fed Ex cares.
Hope that helps 
>>I'm in the process of getting Fed-Ex certified. I was going to use the Superior Enterprises boxes that have individual pieces of styrofoam. Has anyone ever had a problem with these for Fed-Ex testing? I know the larger solid styro lined box would be stronger, but that isn't the box I want to use.
>>Thanks Mike
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John Dague
JD Constriction
www.jdconstriction.com