I painted the backdrop with an old sky blue housepaint that we bought 20 years ago and never used because the blue did not suit our room. I rarely through anything out, so glad I didn't. After 20 years, it needed stirring for a long time to get smooth, but it worked. Painting was not that easy - trying to get a gradient from white on the bottom to blue on the top. It ended up more one color and the top is not as blue as I hoped, but we'll see. I made a few clouds - not too much, again I may add more later. I plan to add buildings, roads etc at the bottom.
At the yard throat, leaving the yard, the track starts to incline up, and turn to the right slightly, then it crosses a ravine using a truss bridge. I bought a double track truss bridge, because even though the track is single track, it will have a slight curve across the bridge, so needs the width to accommodate the curve.
The ravine construction consists of a 1" foam piece glued to the framework underneath.
This will be the river bed, and I marked and carved out the river bed from the foam. I will be painting and glueing rocks etc in the river bed, then adding a piece of glass on top for the water surface.
On top of the glass, I will add fake water resin for a texture, but still allowing you to see the river bed below in 3D.
Next steps will be to lay the trackbed for the track crossing the river.