I made a table topper with the double wedding ring pattern out of Georgia Bonesteel's first "Lap Quilting" book. She sets it up differently, where the middle of the block is divided into two pieces, which may make it easier.
It wasn't too bad sewing the curves, but it was time consuming to cut out the pieces.
Before that I tried a miniature block out of the book "501 Quilt Blocks", and it wasn't salvageable. I think I tried to run before I could walk. I don't know exactly what went wrong, but I suspect my seam allowances weren't accurate enough. The middle bubbled up and it WOULD NOT lay flat, so I tossed it and started the larger one.
I've also seen patterns where the arcs were paper pieced, then sewn by regular methods onto the melons. There is one free online somewhere, I think.