If we are going to build a wall, can we just do it right? It needs to be tall, at least 20 meters, and there needs to be a road along the top, wide enough for two chariots to pass without slowing down - say ten meters. It should be stylish, continuously decorated with murals extolling the many virtues of the USA. There should be flower beds on the US side, carefully tended by gardeners from down south.
It could be paid for with a wealth tax on billionaires only - say 2 % of net worth per year..