I wanted to include some town buildings on the backdrop behind the Thomaston station, freight house, and transfer tracks, so I chose a backdrop from LARC Products called "Steeple" that had several wood-framed houses and a church in the mid-distance, with a meadow in the foreground. There were two complications to deal with on this section. First, the tall foreground trees meant for a lot of finicky knife work to remove the sky portion. It took nearly seven hours just for this 9' section, spread out over several evenings.
Second, the sky in the "Steeple" image is very pale, almost white in fact. Even though I'm removing the sky portion, the hints of sky visible through the tree branches were too much of a contrast with the blue that was used to paint the sky, so I decided to repaint the sky to be much paler toward the horizon.
This time I used three colors: the same Benjamin Moore "aqua marina" and "jet stream" plus a 1:1 mix of "jet stream" and white for the lowest band. The bands were brushed on and then blended while still wet. Here's how the bands looked before and after blending; the colors look different because the "before" photo was taken at night under room lighting while the "after" photo was taken with daylight coming in the windows.
After the new sky dried the background image was applied. LARC offers three choices of material: a 4 mil vinyl, a 7 mil polyester they call "Fab-Tex", and a more rigid 10.5 mil "anti-curl" material. The first two are self-sticking. I chose the 7 mil polyester and was glad to find that it was very forgiving. It practically smooths itself during application, and it's even re-positionable so that you can take it up and reapply it if you do it wrong the first time (which I certainly did!). Here's the result:
I'm really pleased with how the backdrop turned out. While I would hesitate to use the sky-removal technique on a larger layout, for a small shelf layout like this one it was manageable.