Jack is making puzzles inspired by Escher's explorations of interlocking negative and positive space. It is not technically accurate to call them "tesselations" but until someone thinks of a sweet pun or portmanteau to come up with a name this sort of thing, we'll just call them "tesselated puzzles". Rev 1.0, using foam as the base material, and using the Craft-Robo as a CNC cutter, is depicted in this instructable. And in this City Paper article. Rev 2.0, using wood as the base material, and cutting the shapes by hand, is underway. They are so much sweeter now, and use 100% non-toxic materials (wood, watercolors, and acrylic finishing spray). A wood-burner is used to create the black lines, and Dr. Ph. Martin's Watercolors are used for the coloring.