Unless you built the diorama with the intent for gorillas to play hackeysack with it, traditional carriers are going to be sketchy at best. UPS and FED-EX both use a 4-6 ft drop from a conveyor belt carrier to a concrete floor as a guideline. No...I'm not kidding. That is the guideline they use (I worked for them). And unless you use a specialized carrier like Vespa Boys, where the value of the item warrants the cost of the specialized shipping. packaging and specialized insurance on the item, you are going to risk damage to that item. This is a roll of the dice at best. My advice would be to contact the carrier, explain to one of the service managers what you want to do and include photos of the item you are shipping. Ask them for their best reccomendation (be prepared and don't be upset if they refuse to ship because of risk) to achieve the packing and best handling of the item. Then...if they accept, include shipping trauma indicators in your packaging. This won't prevent the item from being damaged as its handled but will give you an indicator as to if it was handled extremely during transit.
It will still have to pass through customs and survive inspection as well as customs repack and handled by the pick up service in the destination country.
A crate is ideal in a case like this but that crate must be able to be handled by whatever shipping company you use.
Good luck.
Mike
"Imagination is the dye that colors our lives"
Marcus Aurellius
A good friend will come and bail you out of jail...but, a true friend will be sitting next to you saying, "Damn...that was fun!"