He started with an old gas tank:
And when he’d finished, it looked like this:
There are full-size versions of both images in the article, together with more pictures and an interview with the artist. Open each image there in a new tab or window for a larger view. It makes entertaining reading, particularly for those who like art that provides a visual illusion and 3D effects.
Obviously, this image depends on viewing it from a specific angle for its effects – it wouldn’t work if seen from any other perspective. Nevertheless, it’s a remarkable achievement, IMHO.