Abstract: A pair of reflector "skins" which are typically thin metal sheets of the order of five feet by eight feet are placed side by side on the bed of a fixture, this bed having a predetermined size and a contour which is typically parabolic. Longitudinal rib members having a "Z" cross section and the same contour as the bed are placed in the fixture on top of the sheets in spaced relationship to each other and running along the longitudinal extent of the sheets. These ribs are secured in position by means of clamps which press the ribs securely against the sheets so that the entire surfaces thereof are held in mating engagement with the fixture bed so that they assume the contour thereof. The ends of the "Z" cross section ribs are secured to each other by means of gussets and clips. The runners of the ribs which abut against the sheets have a series of small holes spaced therealong.