Three Options

After creating your basic box, cut and shape lengths of 1 x 2 lumber to create a frame for the plywood side panels. Use the bracket design shown, or use metal brackets securely attached to your house.

After creating your basic box, cut and shape lengths of 1 x 4 and 1 x 2 lumber to create a frame for the plywood side panels. Use the bracket design shown, or use metal brackets securely attached to your house.

After creating your basic box, trace a wave onto a length of 1 x 8 cedar. Cut along the line with a scroll saw, then separate the pieces to create a gap. Position the boards and nail to the plywood box.

Use brackets or screws to attach the box to your home.