When I was in school for architecture back in the late 90's, 3D printers were state of the art, expensive as all get-out, and really, really finicky to work with. We're not quite at consumer-level pricing yet, but we're already close enough that legislation to stop individuals from 3D-printing firearms.
Here's a better idea: don't print guns, print pizza. That's exactly what Systems & Materials Research Corporation recently received a $125,000 NASA grant to do.
Using a series of powders and oils with various nutritive properties, the printer will print out the pizza in stages, reports this story from rt.com.
The printer will first print a layer of dough, which will be cooked while being printed. Tomato powder will then be mixed with water and oil to print a tomato sauce. The topping for the pizza will be a "protein layer" which could come from any source - animals, milk, or plants.
The cartridges are intended to have a lifespan of 30 years, allowing astronauts (or earthlings!) to enjoy freshly printed meals even on long voyages.
I'll have one pizza, please, extra protein layer. And if it's not printed in 30 years or less, you'd better deliver it free.