Sergey wrote up this neat instructable on making a simple puzzle from paperclips -
As a kid growing in Soviet Russia before Perestroika began, there were not that many toys, games and crafts available to you.
This puzzle is an example of the game that we were making using simple tools from father’s toolbox and regular paper clips (bureaucracy provided infinite supply of paper-clips so they were quite easy to get)
As the author mentions, fun projects like this can definitely help one to think outside the box. One of the commenters mentions making a bigger version out of wire coat hangers – good idea! – Puzzle made of paper-clips