Some ink drawings from May 11, 2013 at 6:32pm.  These are each about 4 inches tall.  I have been doing a lot of drawings in this size lately.  I have been using Prismacolor markers with a brush tip and they have the ability to make these incredibly thin lines.  The extreme pressure sensitivity has lead me to experiment with chair and desk height to get the optimal arm position. I have good results on a low lap desk that allows my whole arm to move.