Lanny Smoot builds lightsabers for a living. No, not like the ones kids used to create with flashlights and plastic tubes—realistic extendable ones, with penumbral edges and laser-blocking abilities. Like an actual Jedi. He’s whipped up giant electromagnetic eyes, too, as well as an omnidirectional HoloTile Floor, which adapts to user movement and—like its spiritual parent, the Star Trek Holodeck—anticipates a world in which users can slap on an AR/VR headset and climb mountains or run marathons...