Artisans who turn ideas into art: Who pickled Damien Hirst's shark and painted Ai Weiwei's seeds?
Cattelan says: 'It only takes a minute to have the idea. After that, I don't do anything. I just keep eating things. In this case, images and information. And then there's a process of selection and separation that's not really conscious. I work more with my stomach than my brain. It's a digestive process. I don't know what of.'