1/ I used 1" thick styrofoam board cut into 1 ft. tiles.
3/ Used a 3/4" square router bit on a drill press set at it's highest speed. It was just fast enough to allow the router bit to carve out the trenches. I also used the same bit to put in the shell hole depressions in no man's land.
4/ Painted the whole lot using a medium brown latex paint. This seals it so afterwards I can use any type of paint.
6/ For trench walls I bought some textured plastic sheets from the hobby store. I painted them and cut them to the desired height and length and again hot glue gunned them in place.
7/ The shell holes walls were built up using latex wood filler (I actually did this before step 4).
8/ For the dirt look of the terrain I used model train powdered earth or burnt grass. It's a very fine coloured powder. I mixed in some dried tea. Yes I said dried tea! Instead of throwing out your tea bags put them somewhere to dry out. When dry simply open up the bags and dump into a storage container. I mixed in some of this tea terrain with the powdered stuff. I found the powdered stuff a bit too fine and the tea (being a rougher and a lighter colour) balanced it off to the effect I wanted to achieve.
9/ Now use an spray bomb glue found in any building center or craft store. Spray the tile surface. Then sprinkle on the terrain powder. Shake of excess. Reapply glue and powder if all areas are not covered. You can also sprinkle the terrain powder on wet paint. I found this works better but remember the paint tends to dry fast so take that into consideration.
10/ I next touched up the trenches with some medium brown flat spray paint.
11/ The barbwire was thin craft wire coiled around a screwdriver shaft. I then dipped the coil into "Black it". This chemical (found usually in hobby stores) carrodes the wire and even rusts it. Nice effect.
12/ I built some posted wire as well. I cut up some 1/16" plastic for bases and drilled small holes for the "posts". Painted the plastic rods grey and then started gently wrapping the carroded wire around them.