When you have little space you need to come up with clever solutions. That is not only true for interior decoration, but for advertising space too.
But how can you turn little space into more? Like this, for exampe:
This is how you turn 9 m² into 27 m².
And 1 billboard into more than just 1 billboard.
This is how it works:
If the billboard is illuminated by green lamps, only the line printed in magenta is readable.
Blue-purple light makes yellow visible.
Red light brings blue to the surface.