Building aircraft has always been a struggle between the size of their components and the need to craft them carefully. More than any other device, airplanes epitomize the concept that “the devil is in the details” because in small errors lies the potential for great mischief such as increased drag and decreased range. The trend is for smoother transitions and, where possible, jointless design. Even the ubiquitous rivet is disappearing, at least from exterior surfaces, replaced by composites that flow uninterrupted from one section to another.

In the past, large structures such as wings, fuselages, or vertical stabilizers were difficult to make alike because there was no good way to measure them. The traditional measuring standard for objects over 20 feet was the theodolite. But theodolites were invented to measure the altitude of weather balloons, not pinpoint the end of a forged spar, 50 or 100 feet distant. Although theodolite measurements can be fairly precise, they are subject to interpretation and as such are not always reproducible. Also, theodolites are slow, and using them can take several days to measure a few hundred points, depending on obstructions.