Since 2007, Bob Duff, 43, has been donning the troopers’ signature white armor as a member of the regional chapter of the 501st Legion, a worldwide Star Wars costuming organization. Mr. Duff’s wife, Tricia, 37, and children Justin, 17, and Alissa, 11, soon joined him as a trio of Jawas, the glowing-eyed, brown-robed scavengers from “A New Hope.”