The guitar seems to have been designed because hemp is more easily molded than wood, but it also serves to create a more sustainable guitar. "Why hemp? The permanent transition from impact sound into airborne sound is essential to the sound. Thats how resonances are formed. This makes Hempstone® the perfect 3 dimensional molding material for music instruments. The material consists of 100 % hemp fibres and contains no plastics, which would close these resonance-gaps."
However, at a cost of €2,850 you would be better off buying a great vintage guitar, which is just as green. There are some other green options if you're looking for a guitar, like the Pop Series by RKS Guitars, or the Martin Sting series. ::Mada Guitars