Vapor or plastic?

Despite being a time-machine, this old register won't let you buy any more.

I was really drawn to this box, and returned to the parking deck a few times before getting the shot I wanted. EXIF doesn't show it, so this was taken with a Canon 600D, 50mm 1.8 lens. Settings were M, 1/13, 1.8, 100 ISO.

Done