A bit hard to see as it is white on white, but it is the hard backing to the large envelope Roland sent his Malerwinkelhaus material in, so an unwitting collaboration, if you like. It was stamped and addressed on the reverse side.
Swiss Post has issued a stamp titled Human Surface, which looks and has the texture of human skin. (Image from Linn's).
"Functionally speaking, the skin is the most versatile organ in a human or animal body. Serving as an interface between the internal and external, it protects our bodies from the environment, presents our "face" to the world, and preserves our inner equilibrium. As well as providing a variety of adaptive mechanisms, the skin also plays an important role in our metabolism and in immunology. The Swiss artist Pamela Rosenkranz is to present an exhibition around this theme at the Swiss pavilion at the Venice Biennale and has also designed this year's stamp (a feature of the event since 2010)."