Abstract: An above-window arch treatment has a series of rectangular slats glued to one another and to a valence so as to form a "peacock's tail". The arch treatment is fabricated by a method which fixes an odd-number of slats about a pivot bolt passing through front and rear valences. The slats are alternated to the right and left of the pivot bolt. The slat most rearward, i.e., immediately adjoining the back valence, is moved perpendicular to the valences. The slats on the right hand side of the perpendicualr slat are sequentially joined to the perpendicular slat and then to each other. Likewise, the slats on the left-hand side of the perpendicular slat are sequentially joined to the perpendicular slat and then to each other unitl the desired arch form is achieved. The assembled slats can then be joined to the front valence or a flower box in front of the arch treatment can be proviced by joining the assembled slats to the rear valence.