Forget Gun Shows. 3D Print Your Own Assault Rifles.
ARS Technica has an interesting article on the fully-legal 3D printing of semi-automatic assault rifles that will fire up to 600 rounds. People are crying about the "Gun Show" loophole, but there are currently no laws on the books dealing with something like this.
I can easily see wealthy drug dealers make a side business by 3D printing disposable assault rifles.