Wire Mountain
Long ago, I decided to use Joel Bragdon's "geodesic scenery" (see http://www.bragdonent.com/index.htm) for mountains and general terrain forming. This method uses sheets of bubble-wrap packing material with the channels between the bubbles filled with urethane foam. Weighing very little, the foamed panels are glued to a framework that can be made of corrugated cardboard or other material.
My first attempt was to begin the skeleton of the mountain that surrounds and hides the staging yard at Roanoke (see the track plan and the Roanoke photo. Space is tight between the raised staging yard and the visible track between Eggleston and Radford, and I had awful visions of narrow cardboard strips collapsing in the breeze. So I tried something different.
I used 9-gauge galvanized steel wire for the vertical profile ribs, and steel poultry wire (1" holes) to support the foamed bubble-wrap. Installing the ribs is easy - I drill 5/32" holes into the top of the benchwork and poke the wire in. Originally I soldered the top wire ring to the ribs, but later decided to attach it with twisted small wire and hold everything together with Goop adhesive.
With the profile ribs in place, I cut sections of steel poultry wire about two or three feet long, and attached them to the ribs with twisted wire and Goop. The resulting assembly is not rigid, but it's sufficient to support the foamed bubble-wrap.
Working with two square feet of bubble wrap at a time, I applied the urethane foam and plastic window screen, then covered it with a sheet of plastic food wrap and weighted the whole sandwich with a piece of plywood. After half an hour, the foam was cured enough to be dry, but was still flexible enough to bend to shape.
I temporarily attached the foam sections to the wire framework to get the shape, and let them cure for another hour. Then they were removed and painted with a coat of flat latex base paint. When this was dry, I used hot-melt glue to attach the foam sections permanently. Ultimately these will be covered with "trees" built in the usual manner (green-painted balls of fluffy material).
This photo shows how the mountain descends behind Eggleston to meet Stroubles Creek, just out of sight to the left. The left end will have a removeable "nose cone" built solely of geodesic foam (no steel supports) to provide maintenance access to Stroubles Creek. Also, the mountain will be just a half-shell, with an open back to allow access to the Danville staging yard.