What you'll need:
- 3/4" plywood
- 1/2" plywood
- chicken wire
- Several cans of "Great Stuff" foam insulation
- Latex paint
- Pull saw
- Nail / staple gun
- Model railroad trees
- Fake snow
Step 1: Build the Frame
I designed the mountain to fit over the existing trackbed and provide a tunnel for the train to go through. For the base, I simply cut a few pieces of 1/2" plywood. To help support t he chicken wire and to add to the height of the mountain, I cut ribs out of 3/4" plywood and screwed them to the base.
Most important was testing the train and track to ensure it would fit through the tunnel without scraping the side.
Step 2: Wrap with Chicken Wire, Stuff with Newspaper
Once the shape of the mountain is complete, stuff the form with newspaper. This will give the spray foam something to stick to. Use as much newspaper as you can and don't worry if you cover the space for the tunnel -- you will be removing the newspaper once the foam dries.