Yes, there were only two layers of sheet metal, 16ga welding metal, between the layers of plywood. The original "design" only called for three layers of plywood but due to the form I bought once cut there were four layers of plywood so i just tacked the extra plywood on the back of the prototype. There are many variations on this idea that could be explored depending on cost and weight goals. I was surprised just how effective the design turned out to be. It would have been nice if I had something larger than the 12ga or 9mm to test with that day since none of the test calibers penetrated all the way.