1. Nail side A onto front and back (make sure all pieces are even at the top).
2. Nail in floor [inset it about .6 cm (1/4-inch.)].
3. Nail on roof. The roof should overhang the back by about 2.5 cm (1-inch).
4. Nail in side B using 2 nails, one through the front and one through the back. These pivot nails must be exactly opposite each other so the side can swing easily.
5. Drill a hole through the front into side B so a double headed nail can be inserted. When you check the box, pull out the "lock" nail and open the side. When you shut the box, replace the nail so the side is "locked".