I know that I could print on ready-scored specialist cardstock, and that I can do this the old-fashioned way using a straight metal rule, but what I really want is a gadget I can put flat cardstock (reasonably heavy -- around the same weight as commercially-available greeting cards) in, wiggle a lever and have it come out neatly scored in a straight line in the right place for folding.

It sounds like the sort of thing that someone should have invented and there should be a demand for, but I can't find one anywhere.

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Leah