This brush is an ideal tool for tracing scanned sketches in Adobe Illustrator. It basically reproduces the pens feel of loosing stroke width at the middle of the tracing line. For proper usage follow the steps below.1) Download the file Inky Pen.ai2) Save it into the brushes folder located under Adobe/Adobe Illustrator/Presets/Brushes
3) Restart Adobe Illustrator (or just open it if it wasn't)
4) Choose Window > Brush Libraries > Inky Pen
5) The "Inky Pen" set of brushes appear in a new tool window.
Thanks to Zefhar