How should I deal with folding and bindery in preparing art?
If you think about a simple letter fold, there are three panels created from a single sheet of paper. Because the paper at each fold compresses slightly, you can’t simply have the sheet in precisely equal thirds–or at least, you can’t do that and have it mechanically folded. Good mechanicals anticipate this, and adjust accordingly: the bottom panel is sized 1/16 inch smaller than the middle, and the middle panel is sized 1/16 inch smaller than the top panel, which then is sized to cover the stack precisely.