Place side rail (B1) in notches on both of the end pieces (C1 and C2). Drill 5/16-inch hole for wooden peg in one of the end pieces. Coat peg with glue and insert it into the hole. Repeat for the notch on the opposite end piece. Drill the holes to a depth of 1-1/4 inches. There will be 1/4 inch of peg left to use for handling. The excess can be trimmed flush with the side rail after the glue has dried.
Photo by Elizabeth Williams