This unusual, Memphis-esque Keystone chair is by Oskar Peet and Sophie Mensen, a/k/a design studio OS & OOS.

"The whole is greater than the sum of its parts? The Keystone project began as an investigation into just that, where loose autonomous objects create balance, which is created through the underlying relationship of the separate elements."

"These parts associate with the three basic elements of a Roman bridge (which for us serves as the best example of when loose parts come together to create a whole); the spanners (elements which connect the bridge to the surface and ensure this foothold does not slide or move), the elemental building blocks, and the keystone (which when inserted completes the fundamental arch shape)."

"Our abstracted and reassembled versions of these three elements lead to the Keystone chair, a chair where there are no physical connections. Only its sheer weight is what holds the whole together."

Though OS & OOS is now defunct (Peet and Mensen parted ways after eight years in business), the Keystone chair is in production by Danish brand Please Wait to be Seated.