with interesting results in engineering simple systems. It applies with a typical bottom-up optimization schema: a system can be divided into subsystems (elemental parts) using tree models; any complex system can be represented in a modular way and it is possible to describe how different physical magnitudes flow through the system; analyzing the different flowpaths it is possible to identify the critical components that affect the performance of the system; by optimizing those components and substituting them with more performing ones, it is possible to improve the performances of the system. A better formulation has been produced during the MAAT EU FP7 Project. A new design method that couples the above bottom-up optimization with a preliminary system level top-down design has been formulated. The two step design process has been motivated by considering that constructal and modular design does not refer to any objective to be reached in the design process. A theoretical formulation has been provided in a recent paper, and applied with success to the design of a small aircraft, the conceptual design of innovative commuter aircraft, the design of a new entropic wall, and an innovative off-road vehicle designed for energy efficiency. See also 3D printing Cellular automaton Configuration design Holarchy Holism Kraftei Modular building Modular construction systems Modular function deployment (MFD) Modular programming Modular smartphone Modular weapon system Modularity Open-design movement Open-source hardware OpenStructures Pattern language Reconfigurable manufacturing system Separation of concerns Systems design Systems engineering System integration References Further reading Schilling, MA., "Toward a general modular systems theory and its application to interfirm product modularity" Academy of Management Review, 2000, Vol 25(2):312-334. Erixon, O.G. and Ericsson, A., "Controlling Design Variants" USA: Society of Manufacturing Engineers 1999 Clark, K.B. and Baldwin, C.Y., "Design Rules. Vol. 1: The Power of Modularity" Cambridge, Massachusetts: MIT Press 2000 Baldwin, C.Y., Clark, K.B., "The Option Value of Modularity in Design" Harvard Business School, 2002 Levin, Mark Sh. "Modular systems design and evaluation". Springer, 2015. Modularity in Design Formal Modeling & Automated Analysis "Modularity: upgrading to the next generation design architecture" , an interview Systems engineering Engineering concepts Design Holism Decomposition methods Open-source hardware