Over the years many techniques have been developed for accurate measurement of part features without reference to an externally calibrated artifact. This tutorial will present a partial survey of such methods for dimensional metrology, their ranges of applications, and their limits. A broad range of applications will be covered, including methods for flatness, squareness, straightness, level, probe ball calibration, and angle and linear scale calibration. The tutorial also attempts to distill the common features of the various methods in the hope that this may provide the basis, or inspiration, for the development of “new” reversals or aid the development of new combinations of techniques to address specific metrology problems. All techniques will be covered first at the conceptual, mechanistic level; then each will be treated with appropriate analytical tools. Most techniques require no more than simple algebra and trigonometry; a small percentage requires mathematical skills typical for graduate engineers.Dr. Chris Evans is Director for the Center for Precision Metrology at UNC-Charlotte and is active in both precision manufacturing and metrology. He previously worked at Zygo Corp and the National Institute of Standards and Technology. Dr. Vivek G. Badami is a Technology Fellow in the Innovations Group at Zygo Corporation where he is focuses on systems architecture, precision engineering, and precision manufacturing for the development of ultra-high precision sensors, optics, and metrology systems.