Abstract: An eyeglass frame supports a pair of mounting adapters. Each mounting adapter includes a connecting mechanism for removably connecting an optical device. The connecting mechanism permits the optical device to be inserted with a low insertion force, but requires a relatively large force for removing the optical device. The connecting mechanism includes an interior bore that accepts an insertion shank on the optical device. A series of Teflon balls are placed in radial channels in an outer wall of the mounting adapter. An O-ring in a groove in the outer wall urges the Teflon balls into the radial channels. The radial channels are shaped to prevent the Teflon balls from falling into the insertion bore, but allow the Teflon balls to protrude partly into the insertion bore. The insertion shank of the optical device has a bevel that forces the Teflon balls out of its path as it is inserted into the interior bore.

Abstract: The invention relates to a method for manufacturing a sheet metal tool that is not planar, and the tools made from the method. A sheet metal blank has a predetermined design of etching resistant material applied to one surface to define exposed areas separated by resist areas. A layer of etching resistant material is also applied to a second surface of the metal blank which overlies at least the exposed areas on the first surface of the metal blank. The exposed areas on the first surface are then subjected to etchant applied from the first surface of the metal blank through the exposed areas to form a tooth shape with a cutting edge. The formed cutting edge terminates in a sharpened surface in the second surface, protected by the layer of the etching resistant material on the second surface of the metal blank.