Sterling silver and Australian salt water crocodile leather.  I designed and made these at university when I was in first year (way back in 2002).  Was thrilled when they were selected as finalist in the national Memento awards and even more chuffed when they took out the prize for Best Australian Memento.  Our previous and current state Premiers both have pieces.  I still make them, so if you are interested please get in touch via the contact page.  Currently working on some similar pieces using Australian native timbers.