Description (with about 60 diagrams) of a suggested instrument, “the contemplation of which can reveal and clarify much about the mathematical basis of music.” The distinguishing idea is not in the material or mechanism (it could be realized as a string, percussion, or wind instrument or as a keyboard) but in the arrangement of the tones in a network of two dimensions (roughly: octaves and fifths). This leads to an extraordinary wealth of enlightenment on the diatonic scale, keys and modes, the tempered scale, and much more. The instrument itself could open new worlds of sound. Anyone is welcome to try to build it!

6.5 x 9.5 in., 36 pages; diagrams. 1988; 2nd printing 1992. ISBN 978-0-934546-45-4.

One of the 60 or so diagrams: a hexagon of related tones:

Plurry: hexagon of related tones

Just one of the ways of actually making the Plurry: a keyboard prototype built by Tim Eisele:

Plurry: Tim Eisele prototype