Mountains will be a major feature of the north end of the railroad, in particular the curve where the top level begins to transition to the lower level.  The look is that of the cliffs viewed when traveling from western NM into AZ in I-40.   They are hued in various shades of red and exhibit the effects of erosion from the centuries.

The process is to create slabs from extruded dense foam, assemble into the basic mountain configuration, and then shape it via file, hot foam cutter, and knife to the raw shape.  Lastly, a shaper is used to refine the rough cuts and achieve the end result before painting and applying washes, etc.

Beginning

Almost at final rough size

I posed the train in the curve to get a sense of proportion.  I actually added another 6 inches. Including the side wall, there are 3 4 x 8 sheets of extruded foam in this corner.

Starting to shape

After the shaping, the open seams will be filled with caulk or plaster soaked paper towels to remove any visible seams before the paint is applied. Once the external wall is done, I will tackle the inner area.