Abstract: A measurement tool for use in creating a customized duct segment for connecting existing adjacent HVAC ducts. The tool includes a handheld unit and a flag, each of which is configured for mounting to a respective duct. A measuring unit, such as a laser rangefinder, of the tool is capable of measuring a linear distance between the unit and the flag, and thus between reference points on the HVAC ducts, such as corners, to which the handheld unit and flag are mounted. The tool is configured to measure and store in its memory multiple distance measurements between multiple reference points. A method of using the tool involves gathering enough measurements between enough reference points, such as corners, that the required configuration for the customized duct segment can be determined, e.g. by CAD/CAM equipment. The tool may include a data port for transmitting gathered data for CAD/CAM purposes.