This tool is used to transfer marks to material using either carbon paper or chalk covered transfer paper. You run this tool over your pattern/design, on top of the transfer paper. It is used more for clothing patterns to transfer the pattern to the material. It is really a dressmaker's tool.
Good idea Maxi for using this tool. I have used it to transfer a design to my material so I can quilt over it. I use the chalk type transfer paper.