I have had some Muslim students who could create portraits of themselves but
they are only able to share these with female students/faculty. The same
goes for photographs. One alternative for a portrait would be to have your
students create a 'representational portrait'. This is really a still life
that represents them in lieu of a portrait of the face. If it is really
personal and accompanied by a statement regarding their religious belief, it
could be much more powerful than showing their face.