The ornamental design for a facial stimulation apparatus, as shown and described.
FIG. 1 is a perspective view of a facial stimulation apparatus according to the present invention;
FIG. 2 is a front view of a facial stimulation apparatus according to the present invention;
FIG. 3 is a rear view of a facial stimulation apparatus according to the present invention;
FIG. 4 is a left side of a facial stimulation apparatus according to the present invention;
FIG. 5 is a top view of a facial stimulation apparatus according to the present invention and wherein the right end view is an inverted mirror image of the left end view;
FIG. 6 is a bottom view of a facial stimulation apparatus according to the present invention; and,
FIG. 7 is a right side view of a facial stimulation apparatus according to the present invention.
The broken lines shown represent unclaimed subject matter and form no part of the claimed design.