Cody R Wilson is a kid who figured out to print a lower AR-15 receiver from a 3D printer that anyone can own.  Which essentially means at any point in time you can order every thing you need to assemble a gun from the internet at home.

I've said it before and I'll say it again. "Technology is scary". With the innovation of the at home 3D printer the door for possibilities has been kicked wide open.

The ability to print out a gun at home is a real possibility now. No registration, no nothing. Just click and print.