The TAPW computer program used for this work is based on the idea of the interference of three waves (each consisting of several waves for the various aspects), one for each light colour, red, green and blue. The interference is subjected to infinite change due to the development of the waves in time and space. The reliefs are snapshots of this dynamic process made at one and the same place. The series as a whole shows how different colours behave according to conditions and chosen points in time. In one relief only two colours occur that are alternately freely distributed or merge into larger, more pronounced farms. Other works show all 12 colours trom the palette Struycken composed. He chose colours at equal mutual distance in the colour circle, all of the same saturation but of different brightness. At times the forms created by groups of small coloured squares appear organic, at others they are geometrie and have a linear definition. The grid, the space separating the Perspex elements from each other, remains dominant, however, and ensures the small coloured squares are seen emphatically as the individual building blocks of the structure.