| 摘要 |
A stereo viewer comprises front and rear sides joined by a common hinge, with intermediate hinges. The front side has a zone with a pair of spaced apart lenses and the rear side has a zone with stereopair in windows. In the storage position the front and rear sides are flat and in the operative position the lenses and the stereopair are in optical alignment. A positioning member is received between the front and rear sides and provides an abutment against the common hinge for determining the operative or viewing position. The front and rear sides and the positioning member may be made of a single sheet of paperboard and the stereo viewer used as a 3-D postcard.
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