The sculpture consists of two elements, an outer steel ring fixed to the fabric of the building, and a steel disc which moves inside it. The outer ring is formed of a series of mild steel 180 x 90mm parallel flange channels, mechanically bent on rollers by the manufacturer, Angle Ring.
The inner disc is formed of a series of 215 x 25mm thick curved stainless steel flats and180 x 25mm mild steel curved flats, bent on rollers and bolted together as T-shaped sections to make the circular form. To prevent deflection under wind load, the disc is braced by 180 x 90mm rhs mullions and transoms and a massive 150 x 250mm rhs cross-beam. The cross beam is the interface between an aluminium curtain wall and an acrylic render finish.
While moving, the disc is held in place by a guide track bolted to its inner flanges. Ten small wheels fixed to the outer ring run in the track and restrain the disc while allowing it to move. The ring is tied back to the circular columns of the main building structure with stainless steel tubes.
The disc is driven by two Bode positioners which are standard motorised units used in industry to rotate chemical tanks. The disc is supported on the drive wheels which project through a slot cut in the ring. To prevent rainwater entering, the outer edges of the ring and disc are sealed with ptfe strip.
The structure was fabricated by Commercial Systems International of Hull, then taken apart to be transported to Stockton by truck, where it was re-assembled. The cross beam was used as a lifting beam to hoist the installation into position.