I add geometry for logos and concepts to models by tracing over inserted images. The current spline command is good to use but if there was a free hand sketch that creates sketch entities on the drag motion of the mouse. Similar to paint but with more control. After completing the free hand sketch and using constraining options you could then further refine the created splines,lines, or arcs with control points. I am not sure if fusion is compatible with a wacom tablet or stylus for surface, but if it was this would be a great feature to use. Solid Edge 2D has this ability.
