Hm, I have a somewhat... radical? - idea on that. Get a bigger hard box - wood, metal, plastic... anything that won't bend, put some popcorn at bottom, cover tightly the faery with stuffing (from a pillow), put it in the box, over the popcorn lair, fill to top with popcorn, push around a bit - so you'd be sure to have filled it good - and close.
Variant 2 - secure with steropor / foam.
Variant 3 - wrap the item with kitchen folio, put it in the box and fill the space with isolating foam. I don't know how to instruct the recipient how to unwrap it. thou... maybe you can cut it carefully after it dries, so the buyer would open it just like the isolation parts of a camera ;) .