In our increasingly IPed world where every copyright seemingly has to be enforced. Who would own the copyright in this instance? The postman? They 'created' it, they weren't instructed to make the piece. Surely postman 1 could sue postman 2 for damaging their 'art'?

I suppose you could argue the 'artist' is akin to a photographer?

But what if another artist joined fedex specifically to 'create' art. Which artist would take precedence? If one broke a box to create art, and one wanted the same box breaking to create art???