# Case Study: 3D Modelling and Printing of a Plastic Respirator in Laboratory Conditions
## 4 Conclusions  
Initially, 3D printers were used by larger corporations to produce prototypes, which were then used to modify the final version of their product to meet requirements. 3D technology is not universally suitable for various types of products. It is only a matter of time before 3D printing produces larger volumes. The advantage of using plastics in 3D printing is the possibility of re-recycling, which is, however, limited by the number of recycles, as plastics become contaminated in some way and when they melt, their properties are degraded. The material can go through five cycles if it becomes unusable. Nevertheless, it can still be used in others, perhaps to produce such precise objects or products--it can still be used as a material [8; 19; 20]. Another interesting material is metal waste, which is sorted, cleaned, crushed to dust, and can be used for 3D printing of metal parts. Of interest is the use of oil used in the preparation of food in McDonald's, where the aim is to process it into a photopolymer resin, which is suitable as a material for 3D printing [21; 22; 23; 24]. There is a need to develop a more diverse biocompatible material with specific biological, mechanical, and chemical properties that can be used for the application of 3D (or 4D) bioprinting. Furthermore, it is necessary to develop 3D technologies with higher speed and print resolution. The production of 3D materials with living elements requires innovative studies that can be revived to introduce new features. The physico-chemical and mechanical properties of 3D printed materials must be further enhanced by changing the chemistry of the photopolymerization or by using additives to produce materials with the desired properties. At the beginning of the 21 st century, the potential and use of 3D printing intensified in the field of medicine. Attempts can be made to produce a functional replacement organ in the body. Today, this potential is at a higher level and the first successful operations with organs produced with the help of 3D printing technology can be seen. It is possible to use 3D printing even during the production of small jewellery. The possibility of producing cars, food, or buildings using this method also comes to mind. In the USA, they started to use this method to produce equipment components for extreme conditions. These are spare parts for the repair of devices for units that are far from civilization. The growing popularity of 3D/4D printing is because in a relatively short time it is possible to produce a wide range of products from various materials and that are \begin{table}
\begin{tabular}{c c c} \hline \hline \multicolumn{1}{c}{**Respirator**} & \multicolumn{2}{c}{**Selected Parameters**} \\ \cline{2-3}  & **Filter** & **Ergonomic Shape** \\ \hline  & & replaceable filters of different materials & two models: suitable for a round face and oval face \\ \hline  & & replaceable & \\  & homemade filters of different materials & most face types \\ \hline  & & Cotton & most face types \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._intelligent for various industries [25; 26; 27; 28; 29]. In 2015, [PERSON] introduced a technique to accelerate 3D printing with Carbon 3d at the University of North Carolina at Chapel Hill. This is an excellent material for 3D printing of prototypes and the production of real and functional parts. It has excellent mechanical properties, high resolution, and exceptional surface quality. Another goal to increase the quality of 3D printed products is to capture errors using a system of sensors and high-speed cameras, which are aimed at monitoring irregularities and then adjust them in real time. The importance of laboratories in research and development is considerable, especially in testing the possibilities of how to improve and enhance 3D printing and in developing a range of materials suitable for 3D printing, as well as exploring its potential in connection with virtual reality [30]. Conceptualization, P.T. and M.P. ; methodology, M.P. and S.K. ; software, M.P. and M.K.