The art of scale-making often involves a search for balance between competing melodic and harmonic interests. Whereas Wilson’s Moments of Symmetry (MOS) and Constant Structures were mainly concerned with the development of scales with melodic integrity – ensuring that each interval spans the same number of steps in a scale – this chapter examines a different approach to tuning that is focused more on harmonic rather than melodic considerations. It provides an in-depth analysis of Wilson’s Combination-Product Sets (CPS), some of his most original contributions to tuning. CPS are highly symmetrical, centreless structures that offer a radically different approach to music that is not organized around a tonal centre or 1/1, but instead relies on the multidimensional interrelationships between its notes to produce coherent harmonic structures.