I have finished the diorama. I didn´t take much photos of that process. But it was very easy and done in one or two painting / building sessions.
1. Cut out a thick quadratic piece of styrofoam (Styrodur) with a hot wire cutter.
2. Melt an uneven and heavy shelled surface with a soldering iron.
3. Add a coat of wood filler, mixed with sand and small stones
4. Paint everything in black or dark brown (I used an airbrush for this work)
5. Drybrush the ground work with different shades of brown
6. Add pigments for more reality
7. Add grass tufts and details like barb wire (1/48 photo etched from Verlinden)
8. Glue on the figs (it was very easy with the long nails attached to their feet, just stick the figs into the foam ground with a bit of white glue)
This is the result. Photos done yesterday at high noon outside.