To make wood shutters, cut three fence slats per shutter to the height of your window, cut two short slats to attach to the front of the shutter, and attach the short slats to the fence slats with a nail gun. Alternatively, use wood screws, drilled in the back of the shutter, to attach the small slats while hiding the heads of the screws.
Use a wood saw to trim the rugged edges off of three fence slats per shutter. Measure the height of your window, and cut the fence slats to match. Lay out the three boards to the desired width, using two pieces of scrap wood to ensure a uniform width between the slats. Measure the width of the shutter, and cut two small slats to match. Use a nail gun to attach the small slats about 8 inches from the top and bottom of the shutter.
Before staining or painting, use a hammer to flatten all of the nails sticking out of the back. Another option is to use wood screws short enough to secure the slats, but not long enough to stick through the front.
For easier construction, push the three slats together, and skip using the scrap wood to maintain a uniform width between the slats. This approach also ensures that the slats hang evenly.