The four robots delicately drawing patterns in a bed of crushed black basalt in Tokyo’s Ueno Park move with such grace that they seem to be purpose-built. But when artist and technologist Jason Bruges acquired them for his work The Constant Gardeners, the robots had already spent years working at a BMW factory in the United States.

“They’re foundry grade, so they’d been welding, riveting, assembling cars,” says Bruges. “They’re having a nice little holiday in Tokyo by comparison.”