Few pics of the progress and after a year of operation. I used 2" foam and a hot knife. Lightly painted with a lighter color for depth of texture. Paint was drylok with cement pigment.
I've kept pictus cats before and loved them, so the cave was planned for them(and they love it), the backdrop is 1" foam to save space but enough for the heater to set back in. Community Tank for the living room with a stock of: