This torso of Avalokiteshvara, made in Nepal around the 17th century, is completely made from flat copper sheet.
The technique used is called "repoussé", French for 'pushed again'. It's a form of embossing in which the craftsman has to create volume from a flat metal surface by hammering alternatively from the front and the back.
Working like this is so demanding and unforgiving (very difficult to rectify mistakes, unlike lost wax metal casting) that it's been mainly abandoned outside of Nepal. The Newari people of Patan, my adoptive neighbourhood, keep the tradition alive. You can see its products everywhere, not only as sacred images, but also as architectural embellishments.
Here's a metalsmith's reference manual from the 18th century. It explains how to join together the different sections of a sculpture and contains many useful tips, for instance that when affixing the head to the torso it should be slightly tipped down. The joins are dovetailed seams with rivets at either end, to make sure they don't split open. They are mainly concealed at the back of the sculpture, but some are visible from the front.
The same 2D to 3D magic is applied by different craftsmen to make everyday products, like trunks, extraction chimneys or money boxes. Sit down in one of these workshops and behold perfect geometric volumes puffing up from galvanised tin sheet, all done by hand.
It makes me think of the 3D printing revolution (RepRap and similar printers): one single material input (polymer, sheet metal), any 3D output. DIY, open-source 3D printers may radically change the way we make stuff, just like the Industrial Revolution did. Meanwhile, in Kathmandu, 3D printers have a name and may offer you a nice cup of tea, if you're lucky.
Robert Cervera Amblar
Sculpture, installation, writing.