Prototyping or materialisation is an expensive stage of Product Design. In a lot of cases, the same technology is both used for the final product and test models; this makes the prototype units very expensive. The use of Additive Manufacturing to build prototypes and small lot parts might be incredibly useful in the future, reducing costs drastically. On the other hand, a large number of units should be build using ordinary methods, being more efficient when it comes to Mass Production. In this thesis, the limitations of Additive Manufacturing are faced creating a method that allows the production of semi-hollow parts. Depending on the AM Technology used and its own limitations, different geometries and parameters may change, allowing the part to be more or less hollow. However, the AM method designed would be the same. The current method has been tested using Fused Deposition Modelling Technology on PLA plastic. The bending beams were successfully printed and tested, giving good results and repeatability. Moreover, having determined that it works on FDM, the same method could be used for Powder Bed Fusion Technology and other AM Technologies.