Bracket for 80mm fresnel lens

Simple right-angle bracket to hold 80 mm round fresnel lens, specifically this one:
"Diameter 80mm Fresnel Lens DIY TV Projection Solar Cooker High Light Condenser"
http://www.ebay.com/itm/191457342889 This particular lens is thick enough to be rigid; the more common rectangular ones are often thin and flimsy.
OpenSCAD included for customization.