French Curve

A French curve is a flat template with a series of irregular, sweeping curved edges, originally a drafting and pattern-making tool that leatherworkers borrowed for the same reason tailors and shoemakers did: hand-drawn curves are hard to make smooth and consistent, and a French curve gives you a repeatable edge to trace or cut against. Rather than one fixed radius like a compass would give you, the various curves along its edge let you match a wide range of shapes — gentle curves for handle ends and rounded flaps, tighter curves for corners and gussets.

In leathercraft specifically, they're sold both as flat plastic templates (like the drafting versions) and as steel or metal rulers, which double as a cutting guide since a knife can run directly along the metal edge without damaging it.

How to use it

1. Line up the section of curve that best matches the shape you're trying to draw or cut — most French curves have several different curves along their edges, so try a few before settling on one.
2. Trace along the edge with a marking tool (or a knife, if using a metal version) to transfer the curve to your leather or pattern paper.
3. For curves longer than any single section of the tool, move the ruler and match the new position to the end of the previous curve so the transition stays smooth rather than kinking at the join.
4. Use it on pattern paper first if you're designing a new project, then trace the finished paper pattern onto leather.

Care

Metal versions need little care beyond keeping the edges free of rust; plastic templates should be kept away from solvents and direct sunlight, both of which can warp or cloud the material over time. Wipe off any adhesive or ink residue after tracing so old marks don't transfer onto future projects.