Builders have submitted their plans for Donald Trump’s proposed Mexico border wall, a key feature of his presidential campaign. Ideas for the 2,000-mile barrier include features like solar panels and booby traps of nuclear waste. Though the project hasn’t yet been funded, the U.S. Department of Homeland Security will soon narrow down the proposals to 20 companies, and those will be invited to build prototypes on federal land near San Diego. Congress is expected to discuss the money for the project this month as part of Trump’s budget proposal. The commander in chief claimed initially that Mexico would pay for the wall, but he has since asked for federal money to build the project. James Carpenter, owner of Texas-based Quantum Logistics, submitted designs that include seismic sensors, drones, and materials that could protect the wall from a car bomb. “Everybody else looks at this as a construction project,” he told the Los Angeles Times. “I look at this from a security standpoint.”