In this film by Norman McLaren, Alexandre Alexeieff demonstrates the pinboard technique of film animation that he and his wife, Claire Parker, invented. The principle, which he explains to a group of NFB film artists and animators, is simply the filming of shadows created when pins (240 000 of them) are pushed out from a perforated white rectangular board to varying heights, so creating gradations of light and dark. The amazing visual effects that can be achieved by this method will fascinate anyone interested in the craft of film animation.