GigaBurr & GigaBurr II
Designed by Bill Cutler 1999, made by Jerry McFarland, level 8.
(left: GigaBurr -Walnut, 2.2 inches; right: GigaBurr II - Cherry, 2.2 inches)
The 250 billion puzzles of this type were enumerated with a computer by Bill Cutler.
The highest level
(moves to remove the first piece)
was 8, of which there were 80 different puzzles,
where only 3 had only 9 internal voids.
Two of these are the
and the third is a symmetric version of the GigaBurr II.
two pieces can go together only one way,
and then visualize the third piece in its final position to determine how to get it in and out.
Here are photos of solving
(the third sequence shows the symmetric GigaBurr-2 made by someone else):