Freeform fabrication and additive fabrication technologies have been combined with subtractive processes to achieve a variety of fully integrated rapid manufacturing systems. The combination of separate fabrication techniques into one rapid manufacturing system results in unit manufacturing process integration, sometimes known as a hybrid system. However, the design methods or approaches required to construct these integrated systems are vaguely described or not mentioned at all. The final product from any integrated system is affected not only by the unit manufacturing processes themselves, but also by the extent the individual units are assimilated into an integrated process. A wide variety of integrated and hybrid manufacturing systems and current manufacturing design methodologies are described in this paper, along with their similarities and differences. Through our extensive review, it was discovered that there are five key elements to a reliable integrated rapid manufacturing system: process planning software, motion system, control system, unit manufacturing process, and a finishing process. By studying the manner in which all other systems have been integrated, a table of successful integrated manufacturing system element combinations has been complied, documenting each of the key element choices, resulting in a variety of modular designs. This paper further discusses the importance of the five elements in manufacturing system integration, and how an integrated system is the way to move forward in the manufacturing domain. To that end, a rapid manufacturing system design methodology was developed that explores designs via process analysis to discover integration potential. Cost-benefit analysis is then used to assess the performance of the new system. This analysis determines if all needs have been met, while staying within the constraints of time and resources. Additionally, a table of common issues and obstacles encountered during manufacturing system development has been compiled to assist in the design and development of future rapid manufacturing systems. To illustrate the design methodology, our modular design experience with a laser aided manufacturing process is presented. Unit manufacturing process integration has increased the productivity and capabilities of our system, which reduced resource volume and increased productivity.