My 2000 puzzle design is Watson's Wormhole, (Copyright Martin H. Watson, 2000. Production of this design is only permitted on a single basis for personal use only. Please contact me for commercial production license, for a 5x5x5 cube with a 1x1x5 void between the centres of two opposite faces.
This puzzle was used as an Exchange Puzzle by Dave Rossetti at the International Puzzle Party in Los Angeles in 2000.
It has a single solution and is very difficult. As yet, January 2003, I am not aware of anyone who has ever solved it manually. It consists of 12 pieces, each formed by joining pairs of planar pentacubes to form non-planar decacubes. Thanks to Rick Eason, Leonard Campbell and Steve Strickland for their analysis work, in confirming that it has one solution, and to Pat Hamlyn for providing initial solutions for filling half a cube.
In 2008, one set of this puzzle sold at auction for $915.