A simple yet effective illusion where the face seems to orientate to the viewer.

View the video to get a good look:
https://www.youtube.com/watch?v=3_YqGBlCFZM
Or check out the illusion virtually on Sketchfab: https://sketchfab.com/models/3ada924493804c8f9817bafe44685533

Most people with always see a positive face in a negative face but
the effect works best with a light source shining on it from the bottom which tricks it as if the light is shining from the top on a positive face. Additionally the standing version also works with a light shining through it from the back. (Like a lithophane effect.)

Remixed from my Melt Face: http://www.thingiverse.com/thing:651829
I squashed, cropped, smoothed and of course inverted it to get a really good illusion effect.

Should print all fine without support.

• IllusionFace-Standing-ca1.1mm.stl
  Thin double sided version that stands.
• IllusionFace-Standing-ca2mm.stl
  Thicker double sided version that stands.
• IllusionFace-Bowl.STL
  A bowl version that can also be hanged on a wall or on a string. Does not work with the light shining through like a lithophane effect.

Note: I printed the thin version fine in natural ABS and 0.2 mm layer height. (except the burn mark at the top) The effect works best with a only slightly reflective material. Use 100% infill for the standing version to make sure there will be no infill pattern shining through, not sure if it will print any infill with any of the standing versions. Don't use a transparent material when you want to have the effect with light shining on it from the bottom. It will not really work with it.