BIR, Inc., a manufacturer of industrial x-ray imaging systems, needed a user manual for its ACTIS computed tomography (CT) system. The manual covers both hardware and software operation as well as hardware installation and setup. Unlike other BIR imaging systems, the ACTIS CT system is designed to be operated by a wide range of users with varying levels of computer expertise. Therefore, the manual had to be written and designed to provide background information and detailed instructions for less technical users, while allowing sophisticated operators to quickly find the advanced information they need. We wrote and designed a manual that describes system operation in detail, with sections of expanded explanation for novice users and embedded "quick guide" instructions for more experienced operators. The text is written in a plain, readable style, and separate sections on advanced theory and operation are included.