Architectural composition is central to most education and training of architects. Hence, though not every architect's role in practice deals directly with architectural composition, all will have a greater likelihood of ability to visualise and understand others'visual concepts than the average client. This text is concerned with the involvement of the client in composition of the building design. The medium of the three dimensional model, manoeuvrable at the computer screen or in Virtual Reality resembles well the intended physical reality of the designed building that the client will either own, use, occupy, or observe and so can assist tremendously. It is suggested that through this empowering vehicle of the CAAC model, far more informed response and tangible, visible vocabulary is accessible to the client to assist dialogue. This text proposes that practice can indicate better participation as a more evident principle. CAAC enables dynamic influences on the architectural composition of the building as accountable, truly potential dialogue towards design outcome from the construction team. The case rests with current exploratory cases of dynamic, participatory architectural composition activity, as a sign for the future.