The last 10 - 20 years have seen major improvements in both the RF performance of Nb3Sn cavities and the cooling capacities of 4 K cryocoolers. In the last few years in particular, these developments have reached a critical crossroads where a single cryocooler can provide enough cooling to operate a single- or even multicell 1.3 GHz Nb3Sn cavity at an accelerating gradient of 10 - 15 MV/m. For a single-cell cavity of this size, this field level corresponds to a roughly 1 MeV gain in beam energy for relativistic particles. This is well within relevant levels for a variety of small-scale accelerator applications in fields such as energy, environmental sustainability, medicine, security and industry. This dissertation describes work that has been done to demonstrate the feasibility of making superconducting radio-frequency (SRF) technology accessible to such small-scale applications, which relies on removing the need for liquid helium as a cooling source. An initial proof-of-principle study was performed, which used a single cryocooler and a single-cell 2.6 GHz Nb3Sn cavity. This experiment achieved the world’s first successful demonstration of an SRF cavity reaching accelerating gradients relevant for small-scale applications while relying solely on a cryocooler as a cooling source. Following the success of this study, a new project was started to extend this concept to a full SRF accelerating cryomodule. The successful design of such a system is described in detail, along with the complete commissioning of the newly designed and fabricated single-cell Nb3Sn cavity which will be used in the cryomodule.