Tracing Wheel

A tracing wheel is a small handle with a spiked or serrated wheel on the end. Run it along a pattern line with a sheet of dressmaker's carbon sandwiched between the pattern and the fabric, and it presses a dotted transfer line straight through onto the cloth underneath — dart legs, notches, pocket placements, anything you need marked accurately before you start cutting or sewing.

I use the serrated wheel almost exclusively rather than the sharp-spiked one; it marks just as clearly without any risk of actually perforating delicate fabric. Worth owning both if you sew a wide range of weights, but if you're only getting one, get the serrated version.

The carbon paper matters as much as the wheel. Use it waxed-side down against the wrong side of the fabric, always on a scrap test first — dark carbon on light fabric can bleed through more than expected, and it doesn't always wash out of every fiber. On fabrics where I'm nervous about marking at all, I'll thread-trace instead, but for a quick, accurate dart or seam marking on a stable woven, the tracing wheel is faster than anything else I own.