Scaffolds are structures used to support the growth of cells in order to replace damaged parts of tissues. They are typically simple structures with a porous arrangement, which allows cells adhesion, but also the flow of the biological fluid. The detailed geometry is, however, defined by the specific application and customized according to the pathology and the patients. Based on their functions, scaffolds are characteristically made of biocompatible and often biodegradable materials. A deep knowledge of the properties of the scaffold, and their peculiarities, is essential for a correct design. This work aims at analysing whether the mechanical behaviour of a typical scaffold structure could be described by referring to properties intrinsic to the system (independent of the geometry/size), or a geometry/size dependency should be taken into account. In the former case, the structure could be treated as an effective 3D material, so that scaffold design could be easily produced and the performance predicted. In the latter, the dependency of the mechanical properties on the scaffold size, as well as on the material, makes the scaffold design more complex. In order to explore this aspect, scaffold-like structures made of poly(lactic acid) have been manufactured using a Fused Deposition Modelling machine. Several specimens with different sizes have been fabricated and their mechanical stiffness and strength measured. The results show that concerning some mechanical properties the structure behaves as a 3D material, whereas for others a geometry/size dependency is clearly observed.