**4. Conclusions**

For many years, 3D devices have been assisting research in very di fferent areas, ranging from simple cell cultures to tissue engineering and drug delivery applications. 2D cell culture represents a chief tool in molecular and cellular biology due to its fast, ease, reproducibility and cheap distinctive characteristic. However, it is now universally accepted that 2D cell culture methods understate the live cells in vivo setting unlike reported for last-generation 3D biomaterials which, on the contrary, are able to mimic in a much more realistic way the environment required for a whole range of biomedical and clinical applications. The development of three-dimensional supports has even greater resonance in tissue engineering and regenerative medicine applications since, in those cases, the function of tissues or organs must be restored ensuring the spatial and functional interconnection between di fferent cell types, in order to guarantee the exchange of gas, nutrients or drugs and the elimination of waste products. In this review, we wanted to highlight how these characteristics can be optimized by merging together the need to provide solid supports capable of assisting cell growth at the level of tissue and organ and, at the same time, the right degree of porosity of the materials that in the specific case of 3D biomaterials offers a whole series of drug delivery capabilities worthy of study and implementation. The way an active molecule is carried to a specific region or cellular type can impact on its interaction e fficacy. Each drug has a therapeutic window in which health benefits must be maximized and side e ffects minimized. This need has materialized in the ever-stricter demand of a multidisciplinary approach for the implementation of new materials and methods for an e ffective in vitro and in vivo drug delivery. Materials science, chemistry and micro/nanofabrication o ffer both original and e ffective solutions applicable in research and clinical areas. The rapid and often inexpensive fabrication of 3DP structures enhances the performance of devices no longer used only as structural supports for tissue regeneration and di fferentiation thanks to the optimization of their intrinsic and tuneable porosity. 3DP mesoporous devices allow an e ffective drug delivery of personalized therapy, customizable both from the geometric point of view and from the point of view of pharmacological requests for each individual patient. With the topics covered in this review, we want to highlight how 3D printing techniques allow the production of CAD designing structures that fully correspond to the request of each patient in response to needs following trauma or pathologies. The future implementation of new biodegradable biopolymers and of multi-step etching processes for post-printing functionalization/modification, will also allow more efficient drug delivery application of sca ffolds as the 3D EBM produced ones, by conferring them the not-yet optimized degree of mesoporosity.

**Author Contributions:** T.L., F.S., M.A. and E.d.F. conceived the review, analyzed the data of literature and wrote the paper. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research received no external funding.

**Conflicts of Interest:** The authors declare no conflict of interest.
