A really nice example of cardboard engineering. This cardboard box was on sale last Christmas in an upmarket retail chain in the UK, and it contained sweets. However we were more interested in the box!
It looks like a Rubik Cube, but since it is a cardboard box, how do you solve it?
The answer lies in the fact that the box is a very clever piece of paper engineering. You open the box, and keep opening it, folding it over, until you find it shows a completed Rubik Cube!
Sometimes called the Milkman's Wallet, this is also similar to the Logic Specs Case, which changes colour when you open it far enough. See http://www.grand-illusions.com/acatalog/Logic_Specs_Case.html