The aim of this research was to implement a computer-aided 3D to 2D pattern development technique for outerwear. A preponderance of total clothing consumption is of garments in this category, which are designed to offer the wearer significant levels of ease. Yet there has not previously been on the market any system which offers a practical solution to the problems of 3D design and pattern flattening for clothing in this category. A set of 3D outerwear templates, one for men's shirts and another for men's trousers, has been developed to execute pattern flattening from virtual designs and this approach offers significant reduction in time and manpower involvement in the clothing development phase by combining creative and technical garment design processes into a single step. The outerwear templates developed and demonstrated in this research work can provide 3D design platforms for clothing designers to create virtual clothing as a surface layer which can be flattened to create a traditional pattern. Point-Cloud data captured by a modern white-light-based 3D body-scanning system were used as the basic input for creating the outerwear templates. A set of sectional curves, representative of anthropometric size parameters, was extracted from a virtual model generated from the body scan data by using reverse engineering software. These sectional curves were then modified to reproduce the required profile upon which to create items of men's outerwear. The curves were made symmetrical, as required, before scaling to impart resizability. Using geometric modelling technique, a new surface was generated out of these resizable curves to form the required 3D outerwear templates. Through a set of functionality tests, it has been found that both of the templates developed in this research may be used for virtual design, 3D grading and pattern flattening.