Hanna Ter Meulen harbors design ambitions as big as a (fashion) house. But on this particular morning, she is hunched over her hands, sewing away on nothing bigger than a little pocket. That's what Italians call a jacket's breast pocket, il taschino, and Ter Meulen, thimble on finger, is finishing off the neatly lined slit in the square scrap of French-vanilla gabardine during a weeklong stint learning Old World tailoring techniques. "You have to stitch really straight," the 23-year-old student says after ironing down the soft piece of fabric. "It's not to be rushed."
Time-honored (and time-consuming) as it may be,...