A method of assembling a retroreflective device comprising arranging a first, a second, and a third reflective surface normal to one another; observing an angular relationship between the reflective surfaces; adjusting the angular relationship between the reflective surfaces; and adjoining the reflective surfaces with supporting members and an adhesive, wherein the supporting members are of substantially the same material as the substrate of the reflective surfaces, have a cross-sectional shape that is complimentary to the edges of the reflective surfaces, and are arranged along the adjacent edges of the reflective surfaces.