Fold-over as a deliberate choice
A fold-over closure has no hardware and no rigid components — the top simply folds and holds. It gives the softest, least engineered look available and it is the lowest-cost closure to produce.
It also holds least securely, which makes it right for presentation pieces and inner pouches, and wrong for anything that has to contain contents unaided through a courier network.
Length is specified from packed height
The fold needs enough length to come down over the contents and still cover. That is calculated from packed height rather than flat height, so send the depth of what goes inside along with its footprint.
Check it on a packed sample: a fold that covers neatly when the pouch is empty can fall short by exactly the thickness of the contents.
