The classic versions of this puzzle consists of 27 small cubes that attach anywhere from 3 to 4 together in various configurations then assemble them in a larger cube of 3X3X3 forming a large cube of 27 smaller cubes. Probably the most well known version was made by Piet Hein and consisted of 7 configurations. They can be assembled in a large cube in a lot of different ways. It also comes in a version that has an added challenge of a checker-board design. Just for fun, I built one using children’s building blocks with the alphabet letters on the sides. Another one I built from dice, so that when completed has all the 1’s on one side, 2’s on another, 3’s on another, etc. I have another called Metropolis that when properly assembled, has the top of buildings and skyscrapers on the top. The possibilities are limited only by your imagination. All you need is 27 identical cubes, an adhesive, Krazy Glue will do and you’re off. Family Games Magna Cube is another variation where a number of magnets have been inserted into some of the cubes so the object is again to build a large cube but these magnets get into the act to increase the challenge. The puzzle comes with the solution but I didn’t find it helpful since it showed only 7 multi-block configurations, but there are actually 8. However, it didn’t matter much as I completed it. By the way, I also assembled it a couple of times but there were magnets showing on the outside. A few more attempts rectified that. I don’t know how many possible perfect solutions exist but I am sure there are more. This is a great variation of a classic puzzle. You can purchase this puzzle at Amazon.