Awesome Puzzle

I recently met a collector of vintage magic devices - and of many other objects.  He showed me this puzzle, which I photographed with my crappy phone camera (I miss my Android phone). The puzzle/trick was was sold as just that, and subsequently used to promote products.  In this case, the products of the  K.M. Supply Company of Kansas City, Missouri.  This particular device is made from wood and metal. 

There are two marbles in the case and the challenge is to separate them - more specifically, it is to get each marble into the holes on either side of the puzzle.  Very hard to do, unless you know the secret - which I believe I gave away in the title of the posting.  The solution is to spin the box - twirl it so to speak.  This forces the marbles easily into their respective holes.  I searched the web and found that it is called a centrifugal puzzle.  My friend said the originals were made by companies such as Adams, and Franco, both toy companies. 

The object is to get these two marbles:

 into small holes on either side of the box:

The solution: to spin (twirl) the box in either direction.  This will force the marbles into the holes.

I found some more recent examples here (where you can also see a good explanation of the puzzle).    This is where I found these:

Homemade model

Moses' Cradle by Skor-Mor.

All Uphill by Thinkfun.