Ramon Bruin is an illustrator from the Netherlands that does some amazing optical illusion drawings on plain sheets of paper, using mostly pencils. Ramon official education was at the Airbrush Academie in Lelystad, where he mastered the art of airbrush, obviously, and yet his big breakthrough came from his 3D optical illusion pencil drawings.
You can easily be fooled to think that the elements in the drawings just want to break through the pages and enter the real world. The effect is achieved by distorting the elements of the drawing, so that when they are seen from exactly the right angle, they seem to be correct, an effect also knows as anamorphic illusion. Another element that really help the illusion is the addition of light source that make you think the elements are casting shadows.