The photo on the left shows the actual pieces of wood before cutting the side vents. They are arranged as they were cut from the one piece of wood. Click on the pictures for a better view. Note that cut "A" is made with the miter angle set to zero, the bevel angle set to 5 degrees. Cut "B" is made with the miter angle set to 5 degrees and the bevel angle set to zero. The floor corners are cut at 45 degree miter and 20 degree bevel. If you have questions about this design, please let me know.
The first step is to glue (waterproof glue, bottle shown) and nail or screw the two sides to the back and bottom as shown. Make sure you have made the 1/4" mounting hole in the back and the two little holes (to use a 1/4"x2" carriage bolt and wire to hang the box on a metal post.) Also, pre-drill for the two pivot screws and the closing screw. Use either 1-5/8" decking screws or 2-1/2" 15 gauge nails (I use a pneumatic nailer.)
Next, loosely fit the front in place. Use two washers as shown to make sure there is room for the door to be open freely when the box is finished. It may be necessary to take a shaving off the door so it will fit easily in the opening.
Now invert the box on the roof as you see on the left. Center the box properly from left to right. Allow more overhang on the front (3.25" in the front and 1.5" on back.) Use a sharp pencil and mark where the box meets the roof. Drill holes (three in the back and two in the front) for screws. Use glue and 5 screws to fasten the roof onto the box.
Here is the completed box with the screw loosened and the door open. You can see detailed plans by going to the Construction Plans section.
Please feel free to send me, Fawzi Emad, any corrections, observations, comments or questions. Thank you! (The tail feather on the left is from Koko, our Blue-Front Amazon Parrot.)