I originally planned to do this project with paint, but after attempting it for my example I switched to colored pencils.
While the the students were finishing up their previous project I took their picture. I set up an old overhead and had them stand at about a 1/4 turn away from the light - giving me the optimal light vs dark on their faces. They could smile, be serious, or even do a silly face! I downloaded those into my computer, changed them to black and white, and then altered the exposure, highlights, and shadows till I got white, one level of grey and black. These were then printed out on 8.5/11 pieces of paper.
The next class we taped drawing paper on top - took a pencil to the window and traced only what we saw. I had the students trace their faces upside down. Many students laughed and asked why and I explained that our brain recognizes faces much too easily and we needed to trick it so that it will see shapes. The students traced only what they saw - lights, mediums, darks. If they could not see their eye they did not trace it!
After tracing their faces many students exclaimed both how awesome and strange it looked!
These are breathtaking - the students worked very hard and are impressed to find that it actually looks like themselves!
(I have permission to use these pictures, but in order to protect my students I have cropped them to make them less recognizable.)