To draw the face was used Inkscape, a vector software, and Gimp, a image editor, both free software.
Now is the time to open Inkscape and start the reconstruction, placing the eyeball. Note that some reference images are placed inside the document. These will help during the drawing process.
The last is the orbicularis oculi muscles. Note that have an image in right side. You can see a good article with anatomical description of a chimpanzee here.
Finished the muscles, it's time to make the eyes.
Put the ears using the reference pictures of juvenile apes.
And the vector drawing is finished.
And to finish all the work, the classical cut image with the skull and the face reconstructed.
The next step will be the reconstruction in 3D of the face. I wait you there.
A big hug!
PS.: Thanks to FAR, that help me with the English.