A: There is a device called an optical printer that allows filmmakers to combine two separate pieces of film—for the Alice Comedies, it would be one featuring the live-action girl and one the animated film—onto a single new strip of film, by use of two projectors and a camera. The Alice live-action bits were filmed in front of a plain white sheet which would then “disappear” when combined with the pencil drawings (also done on white paper).