If you think 3D printers have given would-be gun controllers the vapors already, just wait until you hear the latest from Cody Wilson, the head honcho of Defense Distributed. He told reporters at the Inside 3D Printing Conference in New York City that the group's latest project — a gun made entirely with 3D-printed parts (except for a metal firing pin) — is just weeks away from success. If Wilson and company can deliver on the promise, it would be an important step beyond their already impressive accomplishments in producing functioning AR-15 lower receivers and "high-capacity" magazines for AR-15s and...