3D printing provides a fast, cost-effective way to produce and replicate complicated designs with minimal flaws and little material waste. Early use of 3D printing for engineering applications in the petroleum industry has stimulated further adoption by geoscience researchers and educators. Recent progress in geoscience is signified by capabilities that translate digital rock models into 3D-printed “rock proxies.” With a variety of material and geometric scaling options, 3D printing of near- identical rock proxies provides a method to conduct repeatable laboratory experiments without destroying natural rock samples. Rock-proxy experiments can potentially validate numerical simulations and complement existing laboratory measurements on changes of rock properties over geologic timescale. A review of published research from academic, government, and industry contributions indicates a growing community of rock-proxy experimentalists. 3D-printing techniques are being applied to fundamental research in the areas of multi-phase fluid flow and reactive transport, geomechanics, physical properties, geomorphology, and paleontology. Further opportunities for geoscience research are discussed. Applications in education include teaching models of terrains, fossils, and crystals. The integration of digital datasets with 3D-printed geomorphologies supports communication for both societal and technical objectives. Broad benefits that could be realized from centralized 3D printing facilities are also discussed.