Puzzle Cutting Techniques

Our son, Conrad, cut this puzzle to illustrate for my article, "Earliest Use of Special Techniques for Making Adult Jigsaw Puzzles." as many special techniques as possible. In all, he was able to cut 21 special techniques into the puzzle. The enlarged image also includes an image of the puzzle's back which makes spottingf the techniques a little easier. The codes relate to my article as well.  Artist is Maxfield Parrish.