If possible find a hallowed out log and take a piece of cedar or similar wood that will be good in the elements. Take a drill and bore a one and a half inch hole or smaller in the middle of the log, preferably using a hole saw that attached to the drill. And afterward cut out two pieces of wood in a four sided even square. Cut out one square for the top of your hallowed out log-screw or nail it in place and then repeat the same for the bottom. Voila there is your simple made-ready to go birdhouse, which you can suspend from a branch with a wire running through a screw-eye attached to top of the roof. Have fun and watch chickadees, downy woodpeckers, titmice and similar birds flock to their new home, made by your own two hands.