"Double cutting" is a technique whereby two different sections of puzzle are cut together so that the pieces become interchangeable between sections. This is the basis of some of the most sophisticated and challenging puzzles made today. But back in the 1930's, an obscure puzzle maker known only as "Grunsaco" cut the display puzzle by double cutting two large sections of 40 pieces each in the sky, and another two large sections of 40 pieces each in the water, so that the pieces are interchangeable from one side of the puzzle to the other. Since there is little color differentiation between the two sky sections, this technique makes the puzzle even more difficult and I am not certain every piece is in its "right" place! in fact, upon disassembling it, some pieces fit tighter than others. In any event, a real challenge to get the puzzle "right"! The puzzle also contains 50 figure pieces, mostly simple in design. See if you can spot the double cut areas! This technique was also used to save cutting time by some puzzle makers.
Besides double cutting, puzzle is interlocking. Inside box cover reads, "Tell your friends about our puzzles. They, too, will enjoy doing them.". And there are instructions to check color match for tight fitting pieces.