I have an even better suggestion...
Hire the pot heads to patrol the border. They get to keep all they confiscate. They will never leave! They will swarm all over the desert. Soon, the border will get filled up, with empty Krispy Kreme & Cheetos bags, plus piles of Snapple bottles, along with some Arizona Iced Green Tea...and it won't be long before we will have our own wall!
Good ideas! That's what I call "thinking outside the bong"! :-)