BoPhoto.com: M8 coder - simple manual handcoding of M lenses. Another useful template to apply lens coding. Some Zeiss and Voigtländer lenses have a small gap at the bayonet, where you can even use paint for the marking, which then holds better and doesn't wear off as quickly. Or you can make the markings on thinner paper and clamp it between the lens and the body. It's a bit fiddly, but perhaps practical for occasional changing.