Using plasticine reinforced with metal, the sculptor René Bertrand, helped by his children, six, seven and eight years old, whose little fingers worked wonders, modeled each character between each shot of an image - and sometimes, as in Bluebeard's wedding, there were a multitude of them. He discovered that by taking three successive gestures on a single image, one obtained an extraordinary flexibility of gesture, but the film was then half done, so the first half is a little arthritic while the rest is magnificently animated