Here's a few shots of a model I've been working on. First I constructed the structure from cardboard and hot glue. Stairs and ladders I cut with the CNC laser are used for spacing between platforms.
I then added some Great Stuff Expanding foam to create the cave-like structures.
... some spray paint...
Here is a test image I took earlier (before the spray paint) with some lighting to get a sense of the forms. Almost ready to go.