[Fig. 6. A single page of the Book of Stamps. It acts as a score that sends instruction to computer application that generates a soundscape based on the type and number of symbols that were stamped onto the page.] The Book of Stamps: Travel Guide for a Sonic Landscaping from Cities to Urban Cultures by Art Clay:

The « Book of Stamps » by the sounds artist Art Clay is a travel guide between sonic landscapes from cities to urban cultures. The sheets of the book provide a “recording surface” and the ink stamps with their various patterns provide the ability to place sounds into the book. Together they act as an interactive tangible interface for a variety of time based musical tasks that form a collaborative composition by its users. There are two sets of ink stamps: The stamps that look like natural things like trees, bushes or stone paths belong to the “Country Sounds” category; Those that look like buildings belong to the “City Sounds” category. By stamping a book page with a combination from both categories, a soundscape is created that will either tend to sound like a city, a country or an urban sonic mix of both. In this manner, sonic spaces are created for each of the pages and when the user turns the pages to other already stamped pages, it lends him or her the impression that they are actually “traveling” between places sonically.

To interact with the Book of Stamps, the visitor is asked to select one of the stamps from either of the two collections; ink it well on the pad by pressing it onto the inkpad several times. After inking the stamp, select an empty square on the page of the book and place the stamp on that square. Press the stamp down with much pressure and then return the stamp to where the other stamps are. Once the stamp is in place, you should hear a change in the sonic landscape. The more the page has been stamped the harder it might be to hear the sound you have placed into the mix by stamping the page. More here.