Decide what size you want for the canvas board. Some of the factors to take in to consideration when deciding this are the location that the painting will be placed, the amount of separate details that will be in the painting, and the type of paint to be used. Some typical sizes for canvas boards are 20 by 24 inches, 30 by 40inches and 40 by 60 inches.
Using a cost-effective wood such as alder, measure 3 or 4inch wide boards to the size desired for the canvas board. Cut the boards at a 45 degree angle with an angle or miter saw.
Take standard wood glue and glue the boards together. Clamp them tightly and allow them to dry at least 24 hours.
After the boards have completely set up and dried, unclamp the wood and scrape off any excess glue. Lightly sand the boards to remove the rest of the glue and any edges and slivers.
Measure and cut a piece of canvas three inches larger than the frame. Try to cut as straight as possible for a good fit.
Use small brad nails or staples to attach the canvas to the boards. Stretch the canvas from one side to the other and keep it as tight as possible.