Tricks of light and shadow

Tracing paper is the best material ever for this layering malarkey! I can cut it, draw on it, layer up washes and it still has that lovely translucency that you just won't get with normal paper. I've found that by using thin layers of acrylic washes on it, I can create a shadow-puppet effect plus a touch of subtle colour. Obviously because of the nature of acrylic as an opaque paint, like gouache, the layers have to be extremely thin.
I experimented with 4 layers of tracing paper, cut to create layered shadows, painted for the same effect and drawn on in black ink to create foreground silhouettes. I loved the effect when I held it up to the light, and on a light-box I can imagine the effect would be even more intense. My favourite part of this experiment is how the light casts a misty glow between the layers, giving an ethereal/eerie effect when the layers aren't completely flattened. It's exactly what I want as a background.