Fabric-marking pens are handy tools for drawing stitch lines, outlines and cut lines. Water-erasable fabric markers are my favourite marking tools; the marks stay put for as long as you need, and you decide when to remove them. To remove marks simply wet them under the tap, with a spray bottle, or with a wet paintbrush (my usual method).
This pen comes in two sizes: thick and fine. The thick pen is my go-to size and is always in my mending kit, but the fine pen is better for tracing lines from stencils when you need a slender marking tool to fit in the gaps, or when you want a fine line.
NOTE: For best results test marking pens on an inconspicuous part of your garment first (e.g. an inside seam), as they can be difficult to remove from certain fabrics. Remove any marks before you iron, as heat could set them permanently. If marks disappear with water but return once you iron them, add more water until they disappear again, then let dry or iron again.
Made in Japan and packaged with paper instructions in a plastic sleeve by the manufacturer.