The notebooks themselves were created by designers Clive Piercy and John Sabel, who filled the pages with large blocks of text, broken only by the occasional macabre photograph or ambiguous artifact taped in place.
[The team] photographed books and shadows and mapped it all out with stills to get an idea of what it would look like when you see through the pages and you see the shadows behind the page and the backlight.
The typography itself was hand-etched into black-surface scratchboard and manipulated during the film transfer process to further smear and jitter it. This transfer was then cut up and reassembled during post production to add a final layer of temporal distress.
"[Fincher] knew that he wanted it to be drawn by hand, because it was from the mind of the killer, and I was taking that further, wanting it to be like the killer did the film opticals himself.”
Even though digital editing and compositing were already commonplace in Hollywood and especially in post-production, Cooper and his team opted to assemble the majority of the sequence by hand, giving it an analog warmth and randomness which may have otherwise been cheapened by digital effects.