I was building an exhibition of miniature sculptures in a glass showcase in a shopping mall. Two showcases were located back to back, so that one could not see through them to the other side. I was working with the first showcase when I heard a surprised shout from the other showcase. Two ladies had stopped to look at the sculptures. One of them did not notice the ongoing construction, and supposed automatically that the showcase would have a glass on the front. When she pointed some of the sculptures to her friend, she suddenly noticed her finger passing through the ”glass”.