With one simple box, you can add three great finishes.
Each of our three variations can be built with a collection of common tools:
Twenty-four 2-inch deck screws
2x2 or 1x1 lumber
1 1/2x1/4-inch redwood lattice or flats
Additional 1-inch brads
Note: Pressure-treated wood is probably not a good choice for this project because of its tendency to warp. Also, if you're using cedar, it measures differently from other lumbers, so instead of using a standard 1x2 for the trim on the top of the box, you'll need to rip a 1x3 to 1 1/2 inches wide.
Begin building the boxes by creating the basic box shown below.
You can make your starter box almost any size. If you will be using insert trays, be sure the dimensions are large enough to accommodate the tray completely.
In general, 1x10 lumber works well for most boxes. Follow the diagram shown. The inside corner blocks are cut from 3/4-inch square stock.
Assemble the box with glue and deck screws. Then drill a dozen or so holes in the bottom for drainage.
You can't beat the simplicity of this painted box and its bracket supports. Choose a color that complements the setting in which the box will be used.
To build it, add trim and cove molding as shown in the diagram below. Build the brackets with 2x2 material. Use a miter box to cut the 45-degree angles, then glue and screw the brackets together. Finish by filling nail holes, sanding the box, and priming and painting it inside and out with exterior paint. See "Putting It Up" (below) for details on hanging your box.
To hang your window box, use heavy-duty metal braces or brackets. Or for the Cape Cod model, use the wooden brackets. Be sure any supports are secured securely to studs in the wall (look for a row of nails in the siding for a clue about stud location). Also add a few screws through the back of the box into the studs.