Abstract: 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.

Abstract: A device is adapted for viewing transparencies disposed circumferentially on a disk. It comprises a case (10) adapted to contain a disk (12). A pin (15) is adapted to mount the disk (12) for rotation within the case (10). The disk (12) may be driven in rotation by virtue of at least one peripheral opening (10F, 10G) in the case (10). A pair of windows (10C, 10D) are disposed in face to face relationship and so that the transparencies (13) can move between them. A front member (11B) on one side of the windows is adapted to support an optical system comprising at least one lens (15) in line with and spaced from the windows. A rear member (11C) is adapted to constitute a shank for clipping the device to an article of clothing. The device may be used and worn as a badge, since the front surface of the case (10) may carry any form of inscription or illustration.