Sign a name to prove something and make a promise to others. I sign my name on a white paper repeatedly and overlay one another until they cannot be clarified any single one. I printed that image on a transparency for a light box as an advertisement. I proved without a target, I promised for no one. They become a mass of whispering with white lights.
I also used the image of the drawing to print the posters and stick them on the window where is between the light box and outdoor. It stops the radiation expand to outside. You only can see this advertisement when you are willing to get closer to it.