public interface IProjectItem 

//create a new FolderConnectionProjectItem
var folderLocationItem = ItemFactory.Instance.Create(@"C:\temp\mydata");
await QueuedTask.Run(() => Project.Current.AddItem(folderLocationItem as IProjectItem);

{
  var templateFileName = "Layout.pagx";
  // Get layout Template Path from the project's home folder and combine it with a file name
  var projectPath = CoreModule.CurrentProject.HomeFolderPath;
  var layoutTemplateFilePath = System.IO.Path.Combine(projectPath, templateFileName);
  // Create a new layout project item with the layout file path
  // Create an IProjectItem using a layout template pagx file
  IProjectItem pagx = ItemFactory.Instance.Create(layoutTemplateFilePath) as IProjectItem;
  // Add the IProjectItem to the current project
  //Note: Needs QueuedTask to run
  Project.Current.AddItem(pagx);
}

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

{
  var reportFilePath = @"c:\temp\Report.rptx";
  //Note: Call within QueuedTask.Run()
  Item reportToImport = ItemFactory.Instance.Create(reportFilePath);
  Project.Current.AddItem(reportToImport as IProjectItem);
}