More and more U.S. warship and submarine parts are being 3D-printed—and now the Navy is going after the “really hard problems,” a top official says. “I could go anywhere in the Navy, and you will see ...

[Ben]’s a 15-year-old who loves engineering and loves taking on new challenges. He’s made some cool stuff over the years, but the high water mark (no pun intended) has to be this impressively ...