A light box is for supporting a stack of essentially transparent sheets including photo material which is insensitive to daylight and sensitive to shortwave light, and a record carrier film having transparent regions in the form of the characters or other representations to be produced and an opaque background to shortwave light. The illumination by the light box facilitates positioning of the record carrier film relatively to the photo material, and a grid can be a further help in positioning. A flash device having an aperture, the size of which corresponds to the size of the character or other representation, is for producing the shortwave light to blacken the photo material corresponding to the selected record on the record carrier film.