Digital calipers have been an important tool in machine shops and hackerspaces for a long time now. Being able to quickly get an accurate length measurement can greatly speed up design and prototyping. While many low-end calipers output their measurement over a serial port, MuTko wanted to make a truly hackable pair of calipers from the ground up.
Of course, the digital variety descended from the much older dial or scale calipers. These gave just as much accuracy, but reading scale calipers in particular took a few seconds longer, and when taking many measurements this could add up quickly. Digital calipers come in a wide range of accuracy and price points and are all based on the same concept: a row of PCB traces on the stationary caliper emit a signal that measures the movement and direction of the opposite caliper using capacitive coupling.
