Described herein is a technique for creating a 3D face model using images obtained from an inexpensive camera associated with a general-purpose computer. The inventive layered system comprises an external porous layer, in which the pore walls of the pores have differing thicknesses. The sensor assembly generates a signal when the one of the first vane portion and the second vane portion is moved relative to the other of the second vane portion and the first vane portion when effected by airflow.