public static Envelope CreateEnvelope( 
   double xMin,
   double yMin,
   double xMax,
   double yMax,
   SpatialReference spatialReference
)

{
  // use the convenience builders
  Envelope env1 = EnvelopeBuilderEx.CreateEnvelope(0, 0, 1, 1, SpatialReferences.WGS84);
  Envelope env2 = EnvelopeBuilderEx.CreateEnvelope(0.5, 0.5, 1.5, 1.5, SpatialReferences.WGS84);

  Envelope env3 = env1.Union(env2);

  double area = env3.Area;
  double depth = env3.Depth;
  double height = env3.Height;
  double width = env3.Width;
  double len = env3.Length;

  MapPoint centerPt = env3.Center;
  Coordinate2D coord = env3.CenterCoordinate;

  bool isEmpty = env3.IsEmpty;
  int pointCount = env3.PointCount;

  // coordinates
  //env3.XMin, env3.XMax, env3.YMin, env3.YMax
  //env3.ZMin, env3.ZMax, env3.MMin, env3.MMax

  bool isEqual = env1.IsEqual(env2);    // false

  // or use the builderEx constructors which don't need to run on the MCT.
  EnvelopeBuilderEx builderEx = new EnvelopeBuilderEx(0, 0, 1, 1, SpatialReferences.WGS84);
  builderEx.Union(env2);      // builder is updated to the result

  depth = builderEx.Depth;
  height = builderEx.Height;
  width = builderEx.Width;

  centerPt = builderEx.Center;
  coord = builderEx.CenterCoordinate;

  isEmpty = builderEx.IsEmpty;

  env3 = builderEx.ToGeometry() as Envelope;
}

{
  //Note: Must be on QueuedTask.Run

  //Build geometry
  Coordinate2D ll = new Coordinate2D(1.0, 4.75);
  Coordinate2D ur = new Coordinate2D(3.0, 5.75);
  Envelope env = EnvelopeBuilderEx.CreateEnvelope(ll, ur);

  //Set symbology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(
    ColorFactory.Instance.BlackRGB, 5.0, SimpleLineStyle.Solid);
  CIMPolygonSymbol polySym = SymbolFactory.Instance.ConstructPolygonSymbol(
    ColorFactory.Instance.GreenRGB, SimpleFillStyle.DiagonalCross, outline);

  var ge = GraphicFactory.Instance.CreateSimpleGraphic(env, polySym);
  var elemInfo = new ElementInfo()
  {
    Anchor = Anchor.CenterPoint,
    Rotation = 45.0,
    CornerRounding = 5.0
  };

  ElementFactory.Instance.CreateGraphicElement(
    layout, env, polySym, "New Rectangle", false, elemInfo);
}

{
  //Create a simple 2D rectangle graphic and apply simple fill and
  //outline symbols.

  //Note: Must be on QueuedTask.Run

  //Build 2D envelope geometry
  Coordinate2D rec_ll = new Coordinate2D(1.0, 4.75);
  Coordinate2D rec_ur = new Coordinate2D(3.0, 5.75);

  Envelope rec_env = EnvelopeBuilderEx.CreateEnvelope(rec_ll, rec_ur);

  //Set symbology, create and add element to layout
  CIMStroke outline = SymbolFactory.Instance.ConstructStroke(
    ColorFactory.Instance.BlackRGB, 5.0, SimpleLineStyle.Solid);
  CIMPolygonSymbol polySym = SymbolFactory.Instance.ConstructPolygonSymbol(
    ColorFactory.Instance.GreenRGB, SimpleFillStyle.DiagonalCross, outline);


  GraphicElement recElm = ElementFactory.Instance.CreateGraphicElement(
    layout, rec_env, polySym, "New Rectangle");
  //Or use Predefined shape
  GraphicElement recElm2 = ElementFactory.Instance.CreatePredefinedShapeGraphicElement(
                            layout, PredefinedShape.Rectangle, rec_env, polySym,
                            "New Rectangle2");
}

{
  //Create a simple point text element and assign basic symbology and text settings.

  //Note: Must be on QueuedTask.Run
  //Build 2D point geometry
  Coordinate2D coord2D = new Coordinate2D(3.5, 10);

  //Set symbology, create and add element to layout
  CIMTextSymbol sym = SymbolFactory.Instance.ConstructTextSymbol(
                ColorFactory.Instance.RedRGB, 32, "Arial", "Regular");
  string textString = "Point text";

  //use ElementInfo to set placement properties during create
  var elemInfo = new ElementInfo()
  {
    Anchor = Anchor.CenterPoint,
    Rotation = 45
  };
  var ptTxtElm = ElementFactory.Instance.CreateTextGraphicElement(
    layout, TextType.PointText, coord2D.ToMapPoint(), sym, textString,
                       "New Point Text", true, elemInfo);

  //Change additional text properties
  ptTxtElm.SetX(4.5);
  ptTxtElm.SetY(9.5);
}

{
  //Create a map frame and set its camera by zooming to the extent of an existing bookmark.
  //Construct on the worker thread

  //Build 2D envelope geometry
  Coordinate2D mf_ll = new Coordinate2D(6.0, 8.5);
  Coordinate2D mf_ur = new Coordinate2D(8.0, 10.5);
  Envelope mf_env = EnvelopeBuilderEx.CreateEnvelope(mf_ll, mf_ur);

  //Reference map, create MF and add to layout
  MapProjectItem mapPrjItem = Project.Current.GetItems<MapProjectItem>()
                       .FirstOrDefault(item => item.Name.Equals("Map"));
  Map mfMap = mapPrjItem.GetMap();
  Bookmark bookmark = mfMap.GetBookmarks().FirstOrDefault(
                        b => b.Name == "Great Lakes");

  MapFrame mfElm = ElementFactory.Instance.CreateMapFrameElement(
                       layout, mf_env, mfMap, "New Map Frame");

  //Zoom to bookmark
  mfElm.SetCamera(bookmark);
}