I occasionally work with a part that has a full radius (20") and start with a contour flange and then trim all edges to mating (to be welded) edges. I add small .050 "tabs" that are half radi to the edges to aid in mating the parts for welding. On a full radius part i need to unbend it to add these. no big deal typically but on a part that has no original edges to select to be the base. My work around has been to crate a cutout that has a straight edge to select. Then i can unbend add my tabs then fill hole and rebend.. Seems unneccesary though.