"Yahoo! News reports, 'Designed by Thomas Rathgeb, a graphic artist who works for Swiss Post, the stamps are made from 120-year-old pines felled in northern Switzerland. 'Rathgeb's design focuses on the sustainability and uniqueness of this natural, living material the structure of the wood, integrated into the contemporary design, produces a different picture on each stamp. This makes each stamp unique, just as each tree is unique,' said Swiss Post."
"The Swiss Post site offers a video clip (WMV) of the production process."