A method of assembling a light handling device that includes a plurality of separate walls for reflecting and that is tolerant of elevated heat and heating cycles. The method provides a fast-set adhesive to portions of the walls that are to be secured together. The method also secures the walls in a temporary fixation device for a time period needed for the fast-set adhesive to set, and removes the walls from the temporary fixation device subsequent to the setting of the fast-set adhesive such that the walls are secured together by the fast-set adhesive. The method also provides another means of securing the walls together that is resistant to degradation caused by elevated heat and heating cycles.