See also perspective effects and Necker cube.
Contributed by David Jonathan Ross
Contributed by Swiss Typefaces
Contributed by D Jones
Contributed by Betty und Betty
Contributed by Arnaud Aubry
Contributed by Benjamin Jackson
Contributed by Jorge Iván Moreno Majul
Contributed by Florian Hardwig
Contributed by Matthijs Sluiter
Contributed by Vegar Bakken
Contributed by Ciarán