Step 1
Place the two 1- by 12- by 24-inch boards on a work surface with the 12- by 24-inch sides flat. Form the flexible curve ruler on one 24-inch side of each board. Form the curve so that it curves gracefully down from the center of the 24-inch sides. The curve should end 4 inches down from the 24-inch edge on each end. Trace along the flexible curve ruler with a pencil to transfer the curve to the top 24-inch edge of each board.
Step 2
Cut the curve off from the two boards with a band saw. Guide the boards through the saw as you follow along the pencil line in a steady motion, just fast enough to allow the blade to cut through the wood to complete each cut. Sand the cut edges with a fine-grit sanding block. These are the side boards.
Step 3
Draw an approximately 2- by 2-inch heart in the center of each curved 24-inch edge of the two side boards. Start the heart 1 inch down from the edge of the board.
Step 4
Drill a 1/2-inch hole through the center of each heart using a drill equipped with a 1/2-inch drill bit. Slide the blade of the jigsaw through each 1/2-inch hole and cut out the heart shape. Sand the cut edges with a piece of fine-grit sandpaper.
Step 5
Place the 1- by 8- by 8-inch boards parallel to each other on a work surface with the inside edges 22.5 inches apart. The 1- by 8-inch ends should be flat against the work surface. These are the end boards. Position the 1- by 8- by 22.5-inch board between the ends. The 8- by 22.5-inch side should be flat on the work surface. This is the bottom. Butt the sides on each side of the ends and bottom to form a rectangular box assembly. The curved edge should be facing up.
Step 6
Drive stainless steel wood screws through the ends and sides into the bottom board every 4 inches with a screw gun. Fasten the sides to the ends in the same manner.
Step 7
Turn the assembly upside down so that the bottom is facing up. Drill a 1/8-inch hole through the center and four corners of the bottom board for drainage using a drill equipped with a 1/8-inch bit.