I found this tutorial in case it's helpful. https://craftycreativefriends.wordpr...lock-tutorial/

The difference is that the pattern shown is half circle & half square. I'd start with my circle size, then trace the square onto it & trim down the 2 sides. Layer over another full circle, then fold the 2 edges over the straight sides. The folded sides end up as straight edges so you can piece as usual.

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