my first attempt at a wavy/scalloped border was on a doll quilt in the appplecore pattern...I did not want to trim the edge apple cores into a straight line so decided to just cut some bias strips and 'go for it' ....it turned out just fine, and was really not that different from a regular rectangular quilt. BTW the scallops were much closer together than these will be.
So the moral of this story is (giggle) if you want a scalloped edge ""Just do it"" (giggle)
