Bracket to hold surplus 5-inch 8-diopter biconvex glass lens upright. Two versions: the one with ribs on the base support has less material, so should print faster. The lens is AllElectronics # LNS-65 http://www.allelectronics.com/make-a-store/item/lns-65/8-diopter-lens/1.html This lens is heavy and not of great optical quality (as you can guess from the price) but OK for classroom optics demo. OpenSCAD files for lens holder are included.