Enterprises in all branches of industry are being required to become more user focused, yet, at the same time, increasing competitive pressure dictates that costs must also continue to decrease. Mass customization and modularity are strategies developed to address this challenge by producing goods and services meeting individual customer's needs with near mass production efficiency. However, while mass customization and modular systems have already been discussed in the literature, reports on practical implementation of the principles of mass customization in businesses can be found only within the last years. It is a challenge of manufacturing to produce variety of products with limited resources. As corporations strive to rationalize their manufacturing facilities and to produce a large variety of products at lower cost, modularity is becoming a focus of attention. Modular products and reconfigurable processes are crucial to agile manufacturing and provide a way to produce a variety of products that satisfy various customer requirements in time. This modular approach promises the benefits of high volume production (that arises from producing standard modules) and at the same time, the ability to produce a wide variety of products that are customized for individual customers. Such modular product design has been stated as being a goal of good design. Mass Customization target is the transformation of knowledge into "new" products or services, thus customizing and adapting first knowledge then the product itself. Customizing knowledge happens through instantiation and adaptation of design prototypes of the products or the component to fit the individual needs of the customer. This thesis. emphasis is placed on mass customization and modularity which can be seen as key strategies for making firms more customer centric. Furthermore, provide an introduction into principles, concepts, and demarcations, for mass customization and modularity. As the case study Aye Birsel.s resolve model for Herman Miller is a very good example for the relationship between mass customization and modularity.