View-Master

In 1939, a new instrument for displaying photographs was introduced to the world. Viewing black and white stereographic images had been around for decades, but inventor William Gruber and his partners found a unique way to utilize a newly introduced color slide film process called Kodachrome.  
Mounting 7 pairs of pictures on a single disk, allowing two slides to be viewed simultaneously, one with each eye, created the illusion of three-dimensional depth perception. They called it the View-Master and rolled it out at the Worlds Fair in New York. It became an instant sensation.