It costs thousands of dollars to ship one pound of anything to space. What if instead of shipping spare parts and tools, you just ship a printer, then print tools and parts on demand? (And customize them as needed?) This is one of the coolest use-case scenarios of 3D printing. This wrench was the first tool printed in outer space, printed by Barry "Butch" Willmore in 2014. The Navy is exploring 3D printing in similar ways because ships at sea face similar challenges to those in space.