I'm very interested in the idea of a sculpture building, and... well, the idea of interior space interests me a lot, and the idea... for example, I made a sculpture with Elena Foster. Did you ever see it? It was... it was a sort of... it opened up. It was called "Open Secret". And when, I think, Gehry and... and Norman saw this and they said, ‘It's... it's an architecture, a piece... it's a building’. I'd love to make it into a building – a building that the whole roof opened, a building that... you know, it... that was like a sculpture but ended up by being a building. I'd love to do something like that. I don't want to get into the mechanical stuff at all, no, not as the real architecture stuff at all.

[Q] Did you use to build tree huts and things when you were a kid?

Oh yeah, everybody does. You know, I built things for the children and so on but I didn't... it didn't mean anything to me though.  Except when I built the "Child's Tower"; that was like that. It was like that; it was like a... a place that you could discover your body in... in a way. And when I built a larger version for the Tate for the... the steel one and the door was too small, I made it bigger. It didn't work when it was bigger; you had to... I mean, squeezing through it made sense so I... I changed it back again. It has to be kind of... it has to be awkward. It has to be a thing that you are conscious of your body in those... those buildings. They're not buildings; they are... they are a development of sculpture. I love the idea of a sculpture which has no outside and has only inside.