It would be useful to be able to export the xaml as DrawingBrush (for use in a ResourceDictionary).
Sample :
<DrawingBrush x:Key="PictoLock" Stretch="Uniform" PresentationOptions:Freeze="True">
<DrawingBrush.Drawing>
<DrawingGroup>
<DrawingGroup.Children>
<GeometryDrawing Brush="#FFFFFFFF" Geometry="F1 M 8.33,3.38L 7.43,1.96C 7.07,1.40 6.32,1.23 5.76,1.59L 4.15,2.62C 3.59,2.97 3.42,3.72 3.78,4.28L 5.16,6.22"/>
<GeometryDrawing Brush="#FFFFFFFF" Geometry="F1 M 3.07,5.75L 9.92,5.75L 9.92,11.20L 3.07,11.20L 3.07,5.75 Z "/>
<GeometryDrawing Brush="#00FFFFFF" Geometry="F1 M 0,0L 13,0L 13,13L 0,13L 0,0 Z "/>
</DrawingGroup.Children>
</DrawingGroup>
</DrawingBrush.Drawing>
</DrawingBrush>
Use :
<Rectangle Fill="{StaticResource PictoLock}"/>