public CIMPointSymbol ConstructPointSymbol( 
   CIMMarker marker
)

await QueuedTask.Run(() =>
{
  CIMMarker marker = SymbolFactory.Instance.ConstructMarker(ColorFactory.Instance.GreenRGB, 8.0, SimpleMarkerStyle.Pushpin);
  CIMPointSymbol pointSymbolFromMarker = SymbolFactory.Instance.ConstructPointSymbol(marker);
});

//The following file formats can be used to create the marker: DAE, 3DS, FLT, EMF, JPG, PNG, BMP, GIF
CIMMarker markerFromFile = await QueuedTask.Run(() => SymbolFactory.Instance.ConstructMarkerFromFile(@"C:\Temp\fileName.dae"));

CIMPointSymbol pointSymbolFromFile = SymbolFactory.Instance.ConstructPointSymbol(markerFromFile);

//Create a stream for the image
//At 3.0 you need https://www.nuget.org/packages/Microsoft.Windows.Compatibility
//System.Drawing

System.Drawing.Image newImage = System.Drawing.Image.FromFile(@"C:\PathToImage\Image.png");
var stream = new System.IO.MemoryStream();
newImage.Save(stream, System.Drawing.Imaging.ImageFormat.Png);
stream.Position = 0;
//Create marker using the stream
CIMMarker markerFromStream = SymbolFactory.Instance.ConstructMarkerFromStream(stream);
//Create the point symbol from the marker
CIMPointSymbol pointSymbolFromStream = SymbolFactory.Instance.ConstructPointSymbol(markerFromStream);

//create marker from the Font, char index,size,color
var cimMarker = SymbolFactory.Instance.ConstructMarker(125, "Wingdings 3", "Regular", 6, ColorFactory.Instance.BlueRGB) as CIMCharacterMarker;
  var polygonMarker = cimMarker.Symbol;
  //modifying the polygon's outline and fill
  //This is the outline
  polygonMarker.SymbolLayers[0] = SymbolFactory.Instance.ConstructStroke(ColorFactory.Instance.GreenRGB, 2, SimpleLineStyle.Solid);
  //This is the fill
  polygonMarker.SymbolLayers[1] = SymbolFactory.Instance.ConstructSolidFill(ColorFactory.Instance.BlueRGB);
  //create a symbol from the marker 
  //Note this overload of ConstructPointSymbol does not need to be run within QueuedTask.Run.
  var pointSymbol = SymbolFactory.Instance.ConstructPointSymbol(cimMarker);