Samer Dabra uses a drawing machine called the AxiDraw and a custom program to generate Impressionistic line drawings of people. The machine builds the portraits using four single lines drawn in the four CMYK colors, one on top of another, with minimal tweaking from Dabra. Rion Nakaya of The Kid Should See This edited together a video of the machine creating drawings.

https://kottke.org/18/10/a-robot-that-draws-algorithmically-generated-portraits