## 6 Conclusions  
In conclusion, the manufacture of moulds using 3D printing is feasible and is becoming increasingly popular in the aerospace industry. The aerospace industry has also integrated additive manufacturing processes from the conceptual design stage to the final use of parts. Both in aerospace and in the automotive industry, additive manufacturing processes are starting to be used for prototypes, spare parts, and moulds because of the advantages they offer. For the design of the composite blade mould, several functional and technological aspects of this aeronautical product have been considered. With the mould being a TDV, when starting the design phase of the manufacturing process it was important to know the role and the way the product would be used to accommodate aspects that dictate the technological process of manufacturing the blade and therefore the design of the mould. Due to the fact that the anti-torque blade mould exceeds the 3D printing size of the Ultimaker S5 printer, a puzzle-like assembly method of sections that fit into the printing space and allow the resulting mould to be correctly and accurately assembled from individual sections was chosen. The sections were bonded together using a polyurethane adhesive, the main advantage being that as the adhesive cures, it also increases in volume, ensuring the tightness of the mould. The manufacture of the anti-torque blade started with the preparation of the elements that are part of it (manufacture of the 3D-printed core) and the preparation of the moulds (lower and upper). The 3D-printed blade core takes the place of a structure for which traditionally PVC foam or moltoprene is used. The advantage of a 3D-printed core is the creation of a hollow cavity, which reduces the overall mass of the aircraft product. The labour involved in making the prototype blade mould was 38 h and amounts to EUR 380. The total investment results in a total cost for the manufacture of the two moulds (MAT-COMP V3-FEMALE and MAT-COMP V3-MALE) of EUR 1027.3. The labour involved in laminating the blade was EUR 440 and the materials used were EUR 680, totalling EUR 1120. Thus, for the manufacture of the prototype of the anti-torque blade, the total production costs were EUR 2147.3, of which 47.84% of the amount was invested in the preparation of the manufacture and 52.16% of the amount was invested in the production of the product \begin{table}
\begin{tabular}{c c c c} \hline \hline \multirow{2}{*}{**Mould Manufacturing Process**} & **Total Production Costs** & **Manufacture of Mould** & **Production of the Blade** \\  & **Costs** & **[Percentage from the Total** & **[Percentage from the Total** \\  & **[EUR]** & **Production Cost]** & **Production Cost]** \\ \hline
3D printing & 2147.3 & 47.84\% & 52.16\% \\ CNC machining & 4553.3 & 75\% & 25\% \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Total production costs. (blade). This represents a major advance over conventional processes (CNC machining) where 75% of the amount is invested in the manufacturing preparation and the rest (25%) in the production of the product. At the same time, this type of 3D-printed mould has a limited lifetime and 15 to 30 blades can typically be manufactured. In conclusion, the feasibility of producing 3D-printed moulds in a short time and at a low cost compared to CNC machining aluminium moulds has been demonstrated. Conceptualization, R.T. and S.-M.Z. ; methodology, R.T. and S.-M.Z. ; software, R.T. and S.-M.Z. ; validation, R.T. and S.-M.Z. ; investigation, R.T. and S.-M.Z. ; resources, R.T. and S.-M.Z. ; data curation, R.T. and S.-M.Z. ; writing--original draft preparation, R.T. and S.-M.Z. ; writing--review and editing, R.T. and S.-M.Z. ; visualization, R.T. and S.-M.Z. ;; supervision, R.T. and S.-M.Z. ; project administration, R.T. and S.-M.Z. ; funding acquisition, R.T. and S.-M.Z. All authors have read and agreed to the published version of the manuscript. This research received no external funding. Not applicable.