Happy Cube

Happy Cubes are a set of mechanical puzzles created in 1986 by the Belgian toy inventor Dirk Laureyssens.

Usually, there is only one way to fit the pieces into a complete cube and it can be reached with various levels of difficulty by trial and error.

The four families of Happy Cube puzzles with names of each puzzle are: While the manufacturer lists the difficulty level of the sets (easiest to hardest) as Junior, Original, Pro, Expert, and within each set ranks the puzzles (easiest to hardest) as listed in the previous section, independent researchers have substantially disagreed with this arrangement saying the manufacturer's difficulty rankings within each set "do not contain any relevant information on the difficulty of the model".

Using P for Pro, E for Expert, and the digits 1 (lower difficulty) to 6 (higher) their rankings are: The basic challenge of the Happy Cubes puzzles is to construct a single perfect cube from the 6 pieces of a single puzzle which share the same color scheme and texture.

Several computer applications exist to aid in the process of designing large structures and finding solutions for them automatically.