If you want to save space on the matboard when cutting out these Corner Samples, you could draw/offset the inside and outside lines closer to the Corner Sample then connect the lines and trace the openings. These lines do not need to be perfect as they are part of the design that will be cut away. In this example, the blue lines are the opening where the top and left are part of the Corner Sample, and the green lines are the outside cut of the Corner Sample.
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