Image: Clarkson/Verda Pesta/Kippen
In contrast to the Hangzhou stool featured above is this - part rocker, part seating, part storage – the U Stool by Richard Clarkson, Zena Verda Pesta and Clay Kippen.  Designed as a stool to encourage "active sitting" in that it engages the participant by gently rocking, allowing the sitter to use their abdominal muscles and feet for support, the stool also uses significantly less energy in the manufacturing process and is compostable.

Images: Clarkson/Verda Pesta/Kippen