This is for a laser cutter. I cut a sheet of these at a time on my K40 Laser. The kids love to fiddle with them (the adults too!) The concept is not mine. I believe it goes back to M. C. Escher, but I don't have a great reference. I found a garden tile that was a tiling turtle, then I drew my own vector image that worked the same way. Happy to answer any questions about how I did the tiling, but probably anyone with some 2D vector skills could make it happen.