goes beyond the straight line.If you're working with paper miniatures – or anything to do with thicker paper that needs to be folded – this is a tool you need to consider.
This is the Crafter's Square Scoring Tool, $1.25 USD at Dollar Tree. It is used to score paper to make it easier to get a precise, crisp fold. You generally use it in conjunction with a straightedge. Score, then fold.
This tool is about 6" long, ending in a rounded tip. It has indentations for your fingertips.
Of course, you can use a dull blade, a plastic knife, a nail, an old pen, maybe even your fingernails to score paper. But you might find it useful to have a proper tool.
Or can you think of an alternate purpose? Sculpting chainmail, perhaps?