What do you do if you start painting and part way through find that your subject matter doesn’t fit your canvas? You can always start over, but this can be discouraging. Another option, if you are painting on panel, is to extend the panel by bolting on another section.
One of my classmates had exactly this problem and Gary thought it would be a teachable moment, so I volunteered to help make and attach a custom cradled panel section.
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Clamps hold the frame true and flat as the glue dries. I used Gorilla Glue and made sure to drill and countersink the mounting screws before assembly.