Although today considered a toy, View-Master began it's
commercial life in 1939 as a home-entertainment medium
intended as much for adults as for children.
Invented by William Gruber and marketed by Harold Graves
through Edwin and Fred Mayer's photo-finishing, postcard,
and greeting card company, Sawyer's, View-Master was a
successor to the stereograph viewer popularized in the
19th century by Oliver Wendell Holmes.
But View-Master was an improvement over the traditional stereograph;
it offered seven stereo views on each reel, compared with the stereograph's one view per card, and provided them in color by using Kodak's (then-) new color transparency film, Kodachrome.
These viewers where made:
© Jonas Janfelt