FreeCAD: Sketching a Lofted and Curved Surface without using the Curves Workbench

Notes
It is assumed that all geometry in the sketch is enclosed within the blue construction frame. This includes all other construction geometry, as well as the visible internal geometry of complex curves (Bezier, Ellipse). If this is not the case the bounding box of the sketch will be larger than the construction frame and the final mapping will be scaled down accordingly.