Our teacher had set up an assignment to challenge our pen tool abilities. In the lecture we trained by following predefined lines, after getting an introduction about the possibilities and strengths of the pen tool. I already had knowledge of the pen tool from Photoshop, but it works amazing with vector graphics. I had fun creating the portrait from an underlying picture of myself. The only trouble I had was the hair, but mostly due to how time consuming it was.
Below is the reference picture, and the final result.