Freezing processes in granitic fractures influence subsurface flow during glacial periods and may therefore be relevant for the long-term safety of nuclear waste repositories in crystalline rock. As direct visual observation of hydraulic processes in natural rock fractures is obviously not possible, an experimental approach based on 3D-scanning and 3D-printing of natural granitic fracture surfaces has been developed. High-resolution surface scans of natural fractures are obtained and the resulting digital model is further supplemented by features to attain a workable test cell. This cell is then fabricated by additive manufacturing using clear resin and thereby enabling an optical monitoring. The experiments were conducted in a climate chamber at -5°C using a 0.05% methylene blue tracer solution as it changes color during crystallization. The freezing process was recorded by rapidly taking pictures with an industrial optical camera that allow for an animated representation of the freezing processes. Image analysis has been applied using threshold-based segmentation to generate binary maps of frozen and unfrozen regions at a spatial resolution of approximately 150 × 150 µm. Initially, expansion of the water due to the ice formation pushed the fracture halves in the test cell apart. This was later prevented by adding a clamping metal frame. Experiments to ascertain repeatability showed different freezing patterns and initiation points for ice forming, though, indicating a highly sensitive if not chaotic system. Further experiments to verify the transferability of results from 3D-printed analogues to real world granitic fractures will be performed by the time of the conference.