This is real wooden stool, which looks impossible from a single point of view only.
James Hopkins also created many sculptures of characters from famous animation films, such as Simpsons, Mickey Mouse or Tom and Jerry, which show them from one point of view only. They break into simple geometric forms if you look from another point. You can see them on artist's site http://www.jameshopkinsworks.com.
The image was found at http://www.jameshopkinsworks.com/perspective24.html.