The mountains had to be painted before the shaping was completed as the intensity of the AZ Sun this time of year quickly degrades unprotected foam. I applied a thinned coat of elastomeric paint to provide a UV barrier and just put up with the extra work in causes in cutting and shaping.

I am using a Tippi foam cutter from for the carving followed by a Sur-Form shaper to dress the rough cuts. A hot knife would work too but I prefer the flexibility afforded by the Tippi's multiple tips (and it's less than half the MSRP).  Additional texturing is from a steel bristled brush.

As I proceeded to build a frame for screening, I created rock outcroppings to cover the supports  as much as possible.  Using pieces of foam, I shaped them as a subassembly before gluing to the mountain.

When the major carving, shaping, and texturing was complete, a made a wash of exterior beige latex and applied with a spray bottle.   After that, a dark wash is applied by spray to increase the sense of depth to the cracks and crevices.   I then used a dry-brush technique to highlight specific areas as needed using reds, oranges, and muted yellows to simulate the red hued mountains in northern Arizona.

After light and dark colored washes and dry brushing.  The entire mountain area was subsequently re-washed with a deeper brown after dry brushing additional muted red and yellows.