NEW YORK — Once emblazoned with the slogan “The World at Your Fingertips,” the View-Master system has been a childhood staple for decades, but it was not originally a toy. Introduced at the New York World’s Fair in 1939, the viewer that looked like a pair of binoculars was actually a stereoscopic projector created to let adults travel, after a fashion, and see world landmarks up close and in exquisite detail without leaving home. The View-Master was the brainchild of Sawyer’s Photo Services in Oregon, a major producer of scenic postcards in the 1920s.