In a quiet corner of the Great Neck Library, a century-old dream took shape—layer by layer, print by print—culminating in a sprawling, Gatsby-era Gold Coast mansion, now on display for the public.

See how state-of-the-art 3D scanning, 3D imaging, and 3D printing techniques came together in this epic effort to fully model Andrew Carnegie's 1903 mansion in the heart of New York City. The Cooper ...