As you can see here in these pictures taken in Tate Modern), Empty Shoe Box is basically what it says it is: an empty shoebox, lid placed underneath, left in the exhibition space to be overlooked, kicked, puzzled about or maybe just removed by unsuspecting visitors.
Gabriel has often said that he likes to disappoint people with his work. I think what he means is that he does not like to play into expectations or to exploit the popularity of one work or exhibition by continuing in the same vein. He used this expression to describe one of his most surprising and confounding works which he first showed at the Venice Biennial in 1993.
At Venice, where artists are always expected to put on their best face, it was a brave act to make such a statement. Gabriel uses shoeboxes at home to house unfinished ideas and projects. Small sculptures and materials he is trying out are kept in these boxes until he feels like working on them some more. For this reason he has also referred to them as like a container for ideas. So the empty shoebox rather than being nothing could in fact be many things.