From the designer...
"Patented in America in 1975, the somewhat swirled pieces of this puzzle by Eldon Vaughn must be disjoined and then put back together. I once found a smaller version of this puzzle about twenty years ago in America, but considered it impossible to solve at the time. We have made a new version maintaining the difficulty of the original and licensed it for the Cast Puzzle series. This is without a doubt among the most difficult of all puzzles."

The key word is "twist".

Don’t use too much force...the pieces should just slide apart. NOB



Separate the 3 parts! And assemble them again.