3D Escher* Puzzle. See pix, its made in three layers...
Made by Crystal Lines, c. 1992. #Pieces not mentioned
Can't tell if anyone else has made it, most likely not.
Even if they tried, which it appears it hasnt been.
Can't blame them, this looks real tough...like 3D chess...
So, though outer box is open, the inner puzzle is sealed...
As you can see, the picture is part of the puzzle, the pieces
put together at the factory, i guess to show it can be done.
*Certainly looks like an Escher lithograph, but on closer
inspection, though it looks a lot like "Relativity", "Escher"
name is not mentioned on the box, so, I can't guarantee its
a genuine Escher image....but the puzzle itself is equally
challenging, imho...