We have designed, built, and recorded data with a custom infrasound logger (referred to as the Gem) that is inexpensive, portable, and easy to use. We describe its design process, qualities, and applications in this article. Field instrumentation is a key element of geophysical data collection, and the quantity and quality of data that can be recorded is determined largely by the characteristics of the instruments used. Geophysicists tend to rely on commercially available instruments, which suffice for many important types of fieldwork. However, commercial instrumentation can fall short in certain roles, which motivates the development of custom sensors and data loggers. In particular, we found existing data loggers to be expensive and inconvenient for infrasound campaigns, and developed the Gem infrasound logger in response. In this article, we discuss development of this infrasound logger and the various uses found for it, including projects on volcanoes, high-altitude balloons, and rivers. Further, we demonstrate that when needed, scientists can feasibly design and build their own specialized instruments, and that doing so can enable them to record more and better data at a lower cost.