This looks like a novel and not immediately intuitive way of trapping air in a narrow space between two plates of metal. Neat. There are other ways of trapping

This looks like a novel and not immediately intuitive way of trapping air in a narrow space between two plates of metal. Neat. There are other ways of trapping air between two pieces of metal. I wonder how this compares against a sandwich of metal-bubble-wrap-metal. Or with styrofoam, or an injectable foam. It would also float. It would also withstand multiple punctures. I imagine it is cheaper than etching metal.