public CIMColor CreateRGBColor( 
   double R,
   double G,
   double B,
   double A
)

/// <summary>
/// Create a mesh symbol that can be applied to a multi-patch feature layer.
/// </summary>
/// <remarks>
/// A mesh symbol is a CIMMeshSymbol object.  Define an array of CIMSymbolLayers which contains a CIMMaterialSymbol layer with the specified properties such as Color, etc.
/// Assign this array of CIMSymbolLayers to the CIMMeshSymbol.
/// ![MeshSymbolOrange](http://Esri.github.io/arcgis-pro-sdk/images/Symbology/mesh-material-orange.png)
/// </remarks>
/// <returns></returns>
public static Task<CIMMeshSymbol> CreateMeshSymbolAsync()
{
    return QueuedTask.Run<CIMMeshSymbol>(() =>
   {
       CIMSymbolLayer[] materialSymbolLayer =
      {
            new CIMMaterialSymbolLayer()
            {
                Color = ColorFactory.Instance.CreateRGBColor(230,152,0),
                MaterialMode = MaterialMode.Multiply
            }
       };
       var myMeshSymbol = new CIMMeshSymbol()
       {
           SymbolLayers = materialSymbolLayer
       };
       return myMeshSymbol;
   });
}