3D printing, a rapid prototyping technology, has great potential for applications in laboratory rock tests, but the low strength and stiffness of 3D printed samples have been one of the key problems that need to be addressed. In order to find a way to enhance the strength and stiffness of 3D printed rock-like samples, GS19 sand and furan resin were selected as printing materials, and sand 3D printed rock-like samples were used as research objects. Based on this, the samples were post-processed using three different methods: vacuum infiltration, low-temperature treatment, and combination of infiltration and low-temperature. Uniaxial compression tests were carried out on these post-processed sand 3D printed rock-like samples to study their mechanical properties, and the reasons for changes in mechanical properties were analyzed at a microscopic level by scanning electron microscopy. The results indicated that different post-processing methods can change the mechanical properties of the samples, and the combination of infiltration and low temperature can significantly enhance the strength and stiffness of samples, which is related to change in the internal cementation state of samples. The findings of the study can provide new research ideas for future application of 3D printing technology in rock testing.