THIS PAPER IS CONCERNED WITH PRACTICAL ASPECTS OF THE DESIGN AND MANUFACTURE OF PREPREG COMPOSITE TOOLING. THE SUCCESS OR FAILURE OF A GIVEN TOOL IS USUALLY DETERMINED BY A COMBINATION OF FACTORS, INCLUDING TOOL DESIGN IN RELATION TO PART CONFIGURATION, MASTER MODEL MATERIAL SELECTION AND CONSTRUCTION, TOOL MATERIAL SELECTION AND PROCESSING, AND SERVICE USAGE CONDITIONS. REASONS FOR TOOL FAILURE RESULTING FROM ANY OR ALL OF THESE REASONS ARE EXAMINED, AND RECOMMENDATIONS GIVEN REGARDING THE MEASURES NECESSARY TO ENSURE CONSISTENT SUCCESS. THE LEVEL OF TECHNOLOGY APPLIED TO TOOL DESIGN AND MANUFACTURE DIFFERS WIDELY ACROSS THE INDUSTRY AND IT IS THE AUTHORS' CONTENTION THAT THE VAST MAJORITY OF TOOL MANUFACTURING OR SERVICE FAILURES ARE COMPLETELY AVOIDABLE, GIVEN AN ADEQUATE LEVEL OF EDUCATION AMONG TOOLING ENGINEERS.