A camera shutter similar in working to the unicum is made as follows. Construct a gi'ooved framework A consisting of a board B with an opening for flange and grooved rails A'. Cut two blades in ebonite, C and D. The lever E, with slots F and G, is made in thin metal. Fasten to A' a cylinder made from a piece of brass tube II, having a well-fitting piston-rod I. (A simple substitute may be made easily by winding some paper tightly around a piece of knitting needle.) Two small rivets, fastened to the blades C and D, pass through the slots F and 6, so that when the piston-rod that is attached to E is forced upwards C is raised and D depressed, thus opening the lens. The return of the rod is caused by the suction due to the release of the press ball.

Construction of Camera Shutter.