Thanks for the quick reply! Unfortunately, Rebuild only creates an approximation to my G3 filleted rectangle. Further, the rebuilt curve's seam was not on the long axis axis of symmetry, unlike the example in your video. I can use Loft instead of Extrude to position the seam of an 'extrusion', but I don't want to be working with a rebuilt approximation to my curve. I guess I need to draw my filleted rectangle by plotting control points if Moi has no way to simply merge curve segments. Also, is there no way to merge surfaces?