@davidrevoy Are all those lines the same width or are you able to vary the line thickness with a ballpoint pen?

@scvalex That's all lines I could do with the Bic "Round Stic M" one of the photo: depending the speed, angle and pressure of my hand. I also take advantage of 'ink blobs', that I smear with my fingers to darken the paper.
It has in final a very large variety of effect and line weight. I love this tool.