These were done for a friend of mine, for his graduation project. He asked me if I could make some illustrations, and he actually used a lot of my work in his final presentation, including these. What's so interesting is that these skestches, although being so very rough, had the most impact on the audience! 

It's important to not underestimate the power of stylistics in your drawings. Some looseness can be a great asset to give images more impact.