That's weird. I remember learning AutoCAD back in the release 10 and 11 days. They used to have this "donut" command that would draw a 2D donut shape using a polyline with thickness, and just two points joined by arcs.

Now I think of it, I think I remember: it used two points, with arcs instead of line segments, and "closed" to get the second arc. I'm not sure if you could force the closing segment back to a straight one, but that could have probably got your "D" shape, if so.