[Nendo](http://www.dezeen.com/tag/nendo) has released a new version of its environmentally friendly SU stool for [Emeco](http://www.dezeen.com/tag/emeco/), adding an interchangeable [cork](http://www.dezeen.com/tag/cork) seat to the design. The material is lightweight, resilient and can be harvested every ten years without causing lasting damage to the trees.