They call it the “mirror moment.” After losing their teeth, patients finally see their smiles again. “When you give them that mirror, you just see all that stress melt away,” says Connor Gibson, who works at RAM, a nonprofit offering free health care. “We see grown men cry sitting in the chair.” The process for getting dentures normally takes weeks, but Gibson, a 22-year-old engineer, helped build a system that uses a 3D printer to make a set in about an hour. He sleeps in the trailer at the pop