Which tool is designed for making outside measurements?

The correct answer is outside calipers, as they are specifically designed for making outside measurements. Outside calipers are used to measure the external dimensions of objects, such as the diameter of a rod or the thickness of a piece of material. This tool features two arms with pointed ends that can be adjusted to fit the object, allowing the user to accurately gauge the outside measurement.

In contrast, inside calipers are designed to measure the internal dimensions of objects, not the outside. Vernier calipers, while versatile and capable of taking both inside and outside measurements, primarily rely on a sliding scale and a main scale to provide precise readings rather than just measuring external dimensions. Micrometers, on the other hand, are more suited for very precise measurements of small external dimensions but have a different structure and application from calipers. Therefore, outside calipers are the most appropriate tool for measuring outside dimensions.