We show the design, simulations, and experimental performance of a 35 GHz electron paramagnetic resonance (EPR) resonator based on a cylindrical cavity with 3 mm sample access. The design is robust; simple to manufacture and maintain; and, with its elevated Q value, well-suited to sensitive EPR experiments using continuous-wave or low-power pulsed excitation. Thus, we make multi-frequency EPR spectroscopy, a powerful approach to deconvolute overlapping paramagnetic species, more accessible.