wood glue or paint sprinkled with sand/cat litter ,then painted in colours Warmaster Romulas has sugested IMHO..
when doing trenches the fact that they are threre means the eneny is going to try and eject them,so the surrounding terrain is going to be blasted ?
like Baron von Lexus said ,look for ww1 insperation ?...you can also get some nice effects with gloss paint and other non watersoluble paints on styrene ,just be carefull not to use it too much
.hope this helps you phil
