Gable end trim

[amddrafting]

The easiest way would be creating it in Google Sketchup and importing it as a millwork symbol.

However, if you don't have that ability then this is a simple way:
-Go to a elevation view of the front.
-Draw a triangle to the size you need for the exterior perimeter of the bracket, make sure it's "closed".
-Draw the shape of the "holes" in the brackets with Poly lines. Again, make sure they're closed.
-Select the perimeter line and covert it to a polyline solid.
-Select the "holes" and convert them to "hole in polyline solid."
-Go back to the 2D Floorplan view and make sure the object is line up in the place you want it with the roof.