There's a war brewing over the use of 3D printers to make unlicensed guns and other firearms. But for the time being 3D printed weaponry is still a novelty, particularly this fully functional crossbow, which was created in a single printing pass, complete with a cleverly designed flexible working trigger.
The only part that didn't come from a 3D printer is the string stretched across the crossbow's arms, and whatever's used for ammo—whether it's a chopstick or a balsa glider. You can download the plans for the bow on Thingiverse if you have access to a 3D printer and want to make your own, but just be aware that its size is limited to the capacity of your hardware. So don't expect to take down anything larger that a caterpillar with it. [trenchPhysics via Hack a Day]