Wood louvres are an effective and attractive way of providing privacy and light reduction on exterior windows. You can see out of the window but people outside cannot see inside. Louvres are available ready made, but you can build them at home for a perfect fit for unusual window frames. It is best to make them in a production line approach for all windows rather than one at a time.
Measure the dimensions of the inner frame where the shutter will install.
Cut vertical frame members to size using a mitre saw. Cut the frame members for all windows at the same time. Measure the width of the window, add 2 inches and cut pieces of wood for the slats from the same 2-by-1 timber.
Set up your table saw and guide to rip saw the horizontal wood down the centre to make strips that are about 1.75 by 0.375 inches thick. Make sufficient strips for all windows. Round the edges of the strips using a half-round bit in your router. Sand the top and bottom surface of the slats using a sander or by hand.
Cut a triangle out of scrap plywood about 18 inches high with two 45-degree corners using your table saw. Place the plywood against the guide on your router table and grip a vertical frame piece against the sloping edge of the plywood. Fix a straight cutting bit with a diameter equal to the width of the slats into the router and set it 1/4 inch above the surface. Slide the plywood along the guide, which pushes the frame piece across the router bit at a 45-degree angle. Test the groove for size by placing a slat into it. Continue to make 45-degree slots at 2-inch centres and repeat for each frame piece.
Sand all pieces smooth. Paint or stain the frame and the slats before assembly. Assemble each louvre by measuring the window opening with the vertical frame held in place, add 1/2 inch and cut the slats for this window to length using the mitre saw. Place the frames on a flat surface, lightly glue the slots and push a slat into each pair of slots. Hold the unit square by measuring opposite diagonals and use clamps until the glue has set.
Place the completed louvre in the window. Hold in place by friction or by self-adhesive Velcro strips on the inside face.
Buy long lengths of 2-by-1 to reduce waste. Make a simple jig with metal pins to automate the cutting of the mitre slots. Sand the ends of the slats if they are too tight to easily push into the slots.
Wear protective gloves and goggles when rip sawing the wood for the slats. Wait until the saw blade has stopped before removing wood from the table saw.