Filled with recently procured government grade A Beef.
Use the Great Wall of China as a Template. Use mines, machine gun pill boxes-—Maybe get some design ideas from the Atlantic Wall built by the Nazis. I propose a new branch of the Military—The BorderGuard. With tanks and armored cars, Drones and copters. It should be air tight—no one slips though. Only check points were people can be photographed and processed—This goes for Americans wanting to go Old Mexico too.