Instrument development has long been a strength of the magnetic resonance community, with creative advances in this area driving new applications and expanding the frontiers of what we can measure. At the same time, fabrication of new instruments is traditionally a highly specialized activity requiring expensive equipment and time-consuming training. These barriers to entry limit participation and slow down progress compared to other types of innovation it is easier to disseminate advances and implement new techniques from other groups. Recent developments in 3D printing and inexpensive electronic components make it much easier to build and modify NMR instrumentation. Making the most effective use of this technology will require freely available designs and detailed instructions on their construction and use, in much the same way that sharing and remixing of pulse sequences has led to rapid innovation and a wide variety of applications. The focus of this presentation will be the design, construction, and testing of NMR probes for solid-state and solution NMR using inexpensive or readily available equipment, as well as strategies for effectively sharing and modifying such designs. A major goal of this line of research is providing a straightforward entry point for more applications-focused labs to do some probe modification. Even though not every NMR spectroscopist has the need to build custom probes, the ability to perform simple repairs and modifications can save considerable time and expense. Engaging with instrument designs also enables researchers to choose the right probe for the experiment and ensure that it is performing optimally. Automated bench testing can provide assurance that the instrumentation is performing as designed without wasting magnet time on preliminary troubleshooting. Mechanical and electronic design considerations, benchmarks, best practices for sharing and using design files, test procedures, and associated code will be discussed.