>>>To do this puzzle requires some manual work, but it's really worthwhile, I assure you.
>>>
>>>Get 20 spheres of styrofoam or something similar, and paste them together, into four pieces, like this:
>>
>>About twelve years ago we had a couple of those in the office, with spheres carved in wood. Usually people in the office solved it in about three to six minutes (being mostly fox programmers :). The story on the box said it was Hamurabi's puzzle, and that it was one of his tests he required from his officers. Those who took longer than seven minutes were "promoted" into camel handlers.
>>
>>And then we had a pilot visiting, and he said that whatever it was, he'd have to solve it within a couple of minutes, because his job forces him to quick 3D thinking etc etc. We told him he was just about six minutes... though it was closer to ten.
>
>I was surprised how long I took to solve this puzzle - after all, it only has four pieces!

Me too. It looks very easy, but then you get yourself into thinking... and then it clicks all of a sudden, or it doesn't.