This is a beautiful, flexible design element from Australia. I spotted photos of the stool online and tracked down all the clues until I ended up at Jon Goulder's website...
"Stak stool, seating, shelving and side table. Stak stool is inspired by the humble milk crate. Stak is a multifunctional furnishing that promotes user interaction in the home office or corporate setting. moulded plantation ply core with rock maple veneer top sheets."
A bit of Jon's bio:
"Jon Goulder grew up surrounded by furniture, both in his family factory and at home. In 1992 he completed and apprenticeship in upholstery and furniture making to become a fourth generation craftsman. He began his professional design career in 1994, designing soft furnishings for large commercial retailers, before moving to Canberra in 1996. He completed a diploma of Art, craft and design in the wood workshop at the Canberra School of Art in 1999. Since then Jon has worked hard to design a body of work that grounds him as a stand out Australian designer."