public CIMColor GreyRGB {get;}

{
  //Note: Must be on QueuedTask.Run

  //Build geometry
  Coordinate2D center = new Coordinate2D(2, 2.75);
  var eabElp = new EllipticArcBuilderEx(center, 0, 1, 0.45,
                                      ArcOrientation.ArcClockwise);
  var ellipse = eabElp.ToSegment();

  //Set symbology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(
                                  ColorFactory.Instance.GreenRGB, 2.0,
                          SimpleLineStyle.Dot);
  CIMPolygonSymbol ellipseSym = SymbolFactory.Instance.ConstructPolygonSymbol(
                            ColorFactory.Instance.GreyRGB, SimpleFillStyle.Vertical,
                                                    outline);

  var poly = PolygonBuilderEx.CreatePolygon(
    PolylineBuilderEx.CreatePolyline(ellipse, AttributeFlags.AllAttributes));

  var elpElm = ElementFactory.Instance.CreateGraphicElement(
    layout, poly, ellipseSym, "New Ellipse");
}