Hi jim
I use mdf 2-3mm thick, stick figures with pva, cover bases with polycell textured ceiling filler. dry. Then paint with bitter chocolate external render paint (water soluble from homebase ), then drybrush with white or a beige cream colour, then patches of pva glue and an appropriate colur of static grass.
Or I have used pva glue on the bases and covered this with fine grit, then paint, dry brush, glue patches and static grass, Silfor type or other.
Hope this is of use.
Paul