Thanks Guys !!!
Mike , the hills are mostly aluminum screen wire stapled to the homasote and formed into a general shape , then rock castings , and hillsides are wet wadded up news paper covered with wet paper towels and then the plaster goes on.
Other hills are stacked and cut foam.
I'll try to take a picture inside the helix so you can see , when I post the painted road and helix mountain.
Mike