Engineers have long been restricted in designing and manufacturing one piece, hollow composite components with complex internal geometry. Complex core pulls in the plastic tool, major concessions made in the actual component design or components joined from several pieces were the early means of producing such components. Progressive thinking led to the use of matrix materials such as sand, salt and wax, which provided a measure of flexibility in allowing designed-in undercut areas. These materials, however, lacked the capability to meet the required demands of dimensional accuracy and internal surface, as well as proving themselves unsuitable for high volume production.The concerns for repetitive dimensional accuracy, quality internal surface and high volume production capability has now been satisfied with the use of low melting temperature metal alloys. The utilization of these materials as a lost-core matrix material to form hollow components has taken hold in the European, and more recently, in the North American automotive marketplace.The “lost core” process is the generic name for this technology. “Metallic Core Technology” is a more accurate reference for the process that, with a well engineered core manufacturing cell, sustains no loss of alloy in carrying out the process.“Metallic Core Technology” is demonstrating excellent production-proven capability in the areas of product quality and process reliability, especially as it applies to injection molded composite components. Though “Metallic Core Technology” is gaining in the manufacture of composite automotive parts, numerous applications in a wide range of industrial markets are also under development. For design and manufacturing engineers to optimally utilize this technology in the 90''s, an understanding of the process and more important, how the component design must be related to the process, must be gained. Attention to these basic items equates to a large degree, the success a company will have in implementing a viable manufacturing operation, producing quality components.The objective of this paper is to introduce the technology and present the design and process considerations necessary to effectively manufacture these one piece, hollow parts.