What we did was draw and cut out our top shape and bottom shape and framed those out so we could inset foam. We used poly extruded foam (pink foam that you find at home depot). We glued the foam to maso that was attached to the framing and then we used great stuff to secure foam to foam. Then with a saw, sure form, and snap off knife in hand I sculpted the formations. After they are sufficiently carved we covered them with muslin and glue to protect the foam from wear and tear through the run of the production. Next we will add texture and a final paint treatment. Check back for production shots soon!
Check out Eclipse's website/blog for more details about the show! http://www.eclipsetheatre.com/