There are two components to a hand-made canvas: stretcher bars and raw canvas cloth. The stretcher bars are simply thin pieces of lumber that fit together at the corners, and you can cut them to any dimensions you desire. There are other advantages to building your own stretcher bars and stretching your own canvas instead of purchasing a ready-made product. Making your own canvas is cheaper, and you can produce more professional results using quarter-round trim.
Sketch a rough drawing of the desired dimensions of your canvas. Use a permanent marker to mark the height of your canvas on a length of 1 by 2 lumber. Use a miter saw to cut a 45-degree angle at both ends, ensuring that your mark is on the outside of the cut. Determine if the remaining piece of 1 by 2 will accommodate the width of your canvas. If so, measure from the outside edge of the lumber and use the miter saw to trim the opposite end, again at a 45-degree angle. If not, use a separate length of 1 by 2 and trim a 45-degree angle at both ends. Repeat this process for the remaining two pieces.
Arrange each stretch bar so they fit together like a picture frame in your desired configuration. Use a staple gun to attach the stretcher bars together at the corners, using approximately three staples on both the front and the back of the seam.
Mark the width of your canvas on a length of quarter-round trim. Use the miter saw to cut a 45-degree angle at both ends. Repeat this process for the remaining three sides of the canvas frame. In contrast to the 1 by 2s, you cannot produce a a corner from a single cut of the quarter-round, so trim the pieces as necessary. Use headless nails to secure the trim at the edge of the frame, spacing them approximately 4 inches apart.
Place the frame on top of a large piece of canvas and trim the edges so that it fits easily over the edge of the bars but does not produce an excessive amount of overhang. Fold the canvas over one of the longer sides of your frame and use the staple gun to staple once in the center of the bar. Rotate the canvas so the other long side is facing you and stretch the canvas as tightly as possible over the edge of the frame. Staple once in the center and repeat with the adjoining sides.
Continue stretching, rotating and stapling, working your way out from the center at each side. Space staples between 1 and 3 inches apart, depending on the size of your canvas. When your canvas is taut and all sides are stapled, fold down the corners at 45-degree angles and staple to the frame.
Make sure you purchase unprimed canvas.
Use caution when operating a miter saw. Ensure your fingers are far from the blade at all times, and brace the pieces of quarter-round trim.