The "Installation View" and the "Union of the Torus and the Sphere" at Dia: Beacon is really a site to see. At first I was hesitant to get close but I did eventually notice a gap between the torus segment and the wall, which I took as a cue that it was ok to into the sculptures… perhaps a bit too subtle? The scale of the sculpture, the texture of the material and a general "cold feeling" gives clues that they are made of iron or steel. The Union of the Torus and the Sphere does not reveal whether or not the segments are solid or composed of sheet metal. There are four more pieces installed in the mezzanine. As I walked into them, I'm reminded of the bent paper exercise from 3D II -- relationships between surfaces, negative space, light, shadow… it was fascinating because of its scale. Here, the user gets to see the thickness of the steel sheets - at least an inch, perhaps an inch and a half.
Here are some photos from Google Images.