Reply to "Color and weathering advice requested for foam retaining walls"

I have built train layouts for MTH and what i would use is thinned out craft  paints from Michaels, start out with a medium brown and work your way through the rust colors and dark yellows, drybrush highlight with a light to med gray . I would practice on a scrap piece and when you are happy with the colors blackwash eveything. One drop of craft paint to thirty drops of water. Remember dont make it to dark you can always add more later.