Folding Pocket Stereoscopes (various)

five collapsible stereoscopes dating from 1920-1940, all made of painted tin, condition varies, (1) German Omniplast viewer from 1938 in mint condition, (2) British Coronet viewer, the cardholder and the lens holder are made of plastic, ca. 1940, in very good condition, (3) unlabelled miniature stereo viewer in used condition, (4) unlabelled viewer with black crackle paint in good condition, (5) ingenious folding viewer for 4.5x10.7cm slides made by Jules Richard from 1915-1920, with shift focus mechanism, in good condition, the etched class screen is broken.