public sealed class Layout : ArcGIS.Desktop.Framework.Contracts.PropertyChangedBase, ArcGIS.Desktop.Core.IMetadataInfo, ILayoutElementContainer, ArcGIS.Desktop.Mapping.IElementParent, System.ComponentModel.INotifyPropertyChanged, System.IDisposable  

//Reference layout project items and their associated layout.
//A layout project item is an item that appears in the Layouts folder in the Catalog pane.

//Reference all the layout project items
IEnumerable<LayoutProjectItem> layouts = Project.Current.GetItems<LayoutProjectItem>();

//Or reference a specific layout project item by name
LayoutProjectItem layoutItem = Project.Current.GetItems<LayoutProjectItem>().FirstOrDefault(item => item.Name.Equals("MyLayout"));

//Import a pagx into a project.

//Create a layout project item from importing a pagx file
IProjectItem pagx = ItemFactory.Instance.Create(@"C:\Temp\Layout.pagx") as IProjectItem;
Project.Current.AddItem(pagx);

//Create a new, basic layout and open it.

//Create layout with minimum set of parameters on the worker thread
Layout newLayout = await QueuedTask.Run<Layout>(() =>
{
  newLayout = LayoutFactory.Instance.CreateLayout(8.5, 11, LinearUnit.Inches);
  newLayout.SetName("New 8.5x11 Layout");
  return newLayout;
});
      
//Open new layout on the GUI thread
await ProApp.Panes.CreateLayoutPaneAsync(newLayout);

//Create a new layout using a modified CIM and open it.
//The CIM exposes additional members that may not be available through the managed API.  
//In this example, optional guides are added.

//Create a new CIMLayout on the worker thread
Layout newCIMLayout = await QueuedTask.Run<Layout>(() =>
{
  //Set up a CIM page
  CIMPage newPage = new CIMPage
  {
    //required parameters
    Width = 8.5,
    Height = 11,
    Units = LinearUnit.Inches,

    //optional rulers
    ShowRulers = true,
    SmallestRulerDivision = 0.5,

    //optional guides
    ShowGuides = true
  };
  CIMGuide guide1 = new CIMGuide
  {
    Position = 1,
    Orientation = Orientation.Vertical
  };
  CIMGuide guide2 = new CIMGuide
  {
    Position = 6.5,
    Orientation = Orientation.Vertical
  };
  CIMGuide guide3 = new CIMGuide
  {
    Position = 1,
    Orientation = Orientation.Horizontal
  };
  CIMGuide guide4 = new CIMGuide
  {
    Position = 10,
    Orientation = Orientation.Horizontal
  };

  List<CIMGuide> guideList = new List<CIMGuide>
  {
    guide1,
    guide2,
    guide3,
    guide4
  };
  newPage.Guides = guideList.ToArray();

  //Construct the new layout using the customized cim definitions
  newCIMLayout = LayoutFactory.Instance.CreateLayout(newPage);
  newCIMLayout.SetName("New 8.5x11 Layout");
  return newCIMLayout;
});

//Open new layout on the GUI thread
await ProApp.Panes.CreateLayoutPaneAsync(newCIMLayout);

//Export a single page layout to PDF.

//Create a PDF format with appropriate settings
//BMP, EMF, EPS, GIF, JPEG, PNG, SVG, TGA, and TFF formats are also available for export
PDFFormat PDF = new PDFFormat()
{
  OutputFileName = filePath,
  Resolution = 300,
  DoCompressVectorGraphics = true,
  DoEmbedFonts = true,
  HasGeoRefInfo = true,
  ImageCompression = ImageCompression.Adaptive,
  ImageQuality = ImageQuality.Best,
  LayersAndAttributes = LayersAndAttributes.LayersAndAttributes
};

//Check to see if the path is valid and export
if (PDF.ValidateOutputFilePath())
{
  await QueuedTask.Run(() => layout.Export(PDF));  //Export the layout to PDF on the worker thread
}