Doc,
I like the look of airbrush for mildew, just do a few spots of green in a few different shades of green.
For moss I dip spanish moss in colored latex (green or light green) and normally add velcro to the bottom of the patch so I can remove it for washing.
Belt sanders give a good aged look and I use spray paint alot instead of actual dirt.
Good luck with it,
Allen H




