and corner piece 24 of top panel 16 shown only in dashed outline the panels are each bent along their edges each panel corner is notched with a generous inner radius r and the edges of the panel are then bent as with a sheet metal brake to form two sharp bends 26 and 28 and a gentle arc in the outer regions 30 of the panel near bends 28 the only other metal work involved in the construction of the panels is punching out holes for handles and mounting hardware typically before bending referring to fig3 a corner piece 24 is shown in solid lines with the outline of its corresponding sheet metal panel shown as dashed lines corner pieces 24 may be formed of molded plastic such as blow molded polyethylene a ridge 32 of about 0 070 inch forms a lip for abutting the edges of the notched corner of the sheet metal for a smooth outer surface ridge 32 is radiused on the upper face of the corner piece to match the radius r of the notch the two exposed sides of corner piece 24 are beveled at about a 45 degree angle to its upper and lower faces to match the bevels formed by bending the sheet metal panel each corner piece 24 is snapped into the notched corner of a panel such that sides a and b extend into the interior channels formed by the bent edges of the panel a section view through a joint between two.