Sitting in an office, or in their own homes, many people don’t notice their building’s ductwork unless there is something wrong with it — it’s too noisy or the air in the room is too cold or too hot.

NEW ORLEANS — In a few years, making ductwork may be as simple as pressing a button on a 3-D computer. Uh oh. That might not have been the vision that members of the Spiral Duct Manufacturers ...