I'm no expert but the one that I am making, sewing by hand, I stop the seam joining the wedges 1/4" from the scalloped end. This leaves room to turn under the curved edges and baste a hem. I did a very small whip stitch around the edges to sew the plates onto the background square.
Leave the seam allowance unsewn to easily turn under the scalloped edges.
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A small whip stitch to sew it down. Can use a hidden stitch or a decorative stitch.
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