Fortunately, building them is not very difficult and should be within the reach of most people. Regardless of the source, good nestboxes have some common characteristics. The wood should be rough surfaced, particularly in the interior of the box. Roofs should slope and overhang the front of the box by several inches to protect from rain and sun. The box should be constructed so that it can be easily accessed for monitoring and inspection.
Ventilation is important as is good drainage.
Location, as they say, is everything and this is particularly true for nestboxes. There are several factors to keep in mind. The location should fit the habitat needs of the species you are attempting to attract, including the surrounding vegetation, height of the box above the ground, and appropriate shelter and cover for fledglings and the availability of food and water. Regular monitoring of each nestbox is recommended to keep an eye on the developing birds. Contrary to what most people believe, approaching or handling the nestlings will not cause them to be abandoned by their parents.