Step 5:
Glue the front and back pieces to the side pieces.

Step 6:
Using the holes you pre-drilled as guides, screw the front and back pieces to the sides with 1 1/3" galvanized screws.

Step 7:
Glue the bottom piece to the bottom of your window box and screw that in place as well.

Step 8:
Sand and prime the window box. It is best to use an oil based primer.

Step 9:
Apply the final coats of paint to finish up.

Dress up your window box
You can use a bed molding or a chair rail to make your window box more decorative. Before you sand and prime, glue the molding onto the box where you want it and use small finishing nails to firmly hold it in place. Then continue with the sanding and priming. After you have painted your window box, use stencils to add a variety of colors.