If you would like to make a nest box, the plans and notes linked below, in PDF format, were originally created by Jim Janssen, past president of the BVBBS. They have been edited since, with the latest versions being April 2021.
The Hole Box is the traditional box. The Slot Box has helped to prevent house sparrows from nesting in the box.
Other websites that have plans are the North American Bluebird Society, NABS Factsheets & Plans and Sialis.com, Nestbox Plans.
If you would like to purchase a BVBBS nest box, go to Buy a Nest Box.
Notes, the same for both boxes.