I've started working on some set pieces of an underground nature for skirmish games like Crom and Strange Aeons. I wanted to do a cave section that led into an older underground chamber.
Everything is mounted on masonite cut to a standard size. Openings are placed in such a way as to make the set fairly modular and simple to expand upon.
The first piece is the entrance: a cave with several chambers to break up the action a bit.
Insulation foam and bark from the yard.
The top can be removed to allow access to the tunnel leading into the caves.
The caves within. I've included a small water course running from the back of the caves out through the entrance.
Next, the inside of a barrow. The circular pits will contain the remains of warriors long past.
Finally a much larger area that will have about 6 opening that can leead to other chambers or passageways. More insulation foam for the walls. The floor was made by peeling off a layer paper on a foamcore board and scribing into the foam with a pencil.