The object is to make a perfect cube from the 25 "Y" shaped pieces that will fit under the nice wooden cover.  This puzzle was invented by David Klarner and published in the Journal of Recreational Mathematics in 1970. Originally it was thought to be solvable 236 ways. Later computer analysis showed that over 1200 ways were possible. This may sound like a lot, but there are millions of was to get close.

Dimensions: 3.4" x 3.4" x 3.4"
Difficulty level: 4 (out of 6)