Kris Temmerman, a freelance creative developer based in Belgium, just published a nice report on how he built a painting machine running on an Arduino Due and an Android tablet.
I was always interested to remove the perfection from computer graphics. So thought it would be fun to try to make the most obvious thing first. A machine that uses a paint brush to print a drawing.
As you can see from the video, Kris was able to translate the pen pressure on the tablet into specific brush strokes on the paper.