When I was a kid, my parents purchased a pair of paintings on glass at a fair, that the artist had painting while they watached, and they hung on our living room wall for decades. I wish I knew what happened to them. The artist had painted the landscapes on the back of the glass, beginning with the foreground details. These paintings were the inspiration for my ideas for the translucent plastic poster board.
I decided to use the translucency to create some atmospheric perspective. One side is very smooth; I will be referring to this side as the front, and the other is slightly textured; this side is the back. I sketched a quick skyline on paper, put it under the translucent board with the back side facing UP, and began by painting yellows and whites for windows and lights.
Meanwhile... the color burst sky on the back of the other piece of translucent plastic poster board had dried, so I flipped it over and, using a black Sharpie on the front, I created this silhouette of a bare tree.
Viewed from the backside, this is what it looks like.