Abstract The objective of this study was to investigate new 3D printable materials, namely PORO-LAY series in both solid and flexible forms, on behalf of their radiological properties by measuring their Hounsfield units (HUs) values at varying infill densities, different infill structures and several kinds of fluids in order to assess their suitability as tissue mimicking materials (TMMs) for phantom applications. In this study, it was found that PORO-LAY materials can be used to achieve low and high values of HU ranges from −990 to +950 depending on their infill density and the filling fluids. In addition, PORO-LAY materials have an acceptable dimensional stability and dimensional accuracy in their solid and flexible forms. The results also indicate that the shape of infill pattern influences the values of HU with percentage difference ranges from 3 to 33% depending on the selected infill structure. The results of this study showed that PORO-LAY materials were feasible to be used as TMMs for CT and PET/CT applications.