If his post office received the item damaged, they will have provided him with a document saying, in official language, "We're soooooorrrrrrry our machine devoured your stuff, k?"
If he produces photos of the damaged package and the note from the post office, I'd refund or replace without a murmur. If he can't, I'd ask him to return the item for a full refund.
Did you ship first class PACKAGE or first class LETTER?
If letter, don't ever do that again - it's for letters, not little bits of plastic, and the machinery your "letter" goes through in the sorting process can destroy tungsten steel, much less innocent little bricks or figs.
If package, how much padding did you use, and was this a poly bubble mailer or a paper mailer (bubble or otherwise)? I have switched entirely to the poly mailers, they are much harder for the post office to mangle to the point of tearing.