Innovative backdrop technique

[velotrain]

Even though very few Japanese layouts / modules have "sky boards", I ran across this image many years ago and saved it as an interesting and effective treatment.  The combination of subdued colors and 3D background buildings creates a very smooth transition.

Of course, you need to be willing to give up a fair amount of layout space to be able to do this.  You could either scratchbuild from cardboard or, the Tomytec  etc. structures  are cheap enough that you could bash them into thinner versions and tone down the coloring.