Bleigiessen was commissioned for the eighty storey high atrium of the The Wellcomem Trust Head Quarters in London. At ground level the atrium has a pool that became the starting point for Heatherwick's thinking. Heatherwick played with the notion of falling liquid, and the German New Year custom of dropping small pieces of lead into a saucepan - the shapes formed have a symbolic and prophetic meaning. Replicating this experiment he found his visual inspiration.

The technical challenge of reproducing such a random but complex form was solved by using scientific scanning technology to map the position, and scale up each droplet. Using data sheets, a metal grid incorporating 27k wires was constructed and anchored each of the 150k droplets. The droplets, made in two parts from cut optical glass, sandwiched a layer of diachronic film, these were thread onto the wires. It took more than 30 people to install the finished sculpture, which is 30m high.

Designer: Thomas Heatherwick