# Case Study: 3D Modelling and Printing of a Plastic Respirator in Laboratory Conditions
###### Abstract  
The importance of 3D printing is primarily that it enables customized production and, through Industry 4.0 technology, enables decentralized production. The article deals with the issue of 3D modelling and 3D printing of plastic respirators in the laboratory conditions of the authors' workplace. In the above case study, the process of creating 3D models of individual parts of a plastic respirator and the production of a given model using a 3D printer is processed. The article also outlines the trends in 3D printing in connection with Blockchain and their importance on the Supply Chain. 3D printing; 3D modelling; CAD software; respirator +
Footnote †: journal: Applied sciences  
0000-0002-4000-0000-0000-0000-0000-0000-0000-0000-0000-0000-00000-0000-0000-00000-00000-0000-00000-00000-00000-00000-00000-0000-00000-0000  
* Immutability: Blockchain can offer a tamper-proof solution;
* Decentralization: Blockchain can prevent them entirely controlled by one party;
* Privacy-preserve: Blockchain can encrypt them by using hashing algorithms;
* Smartness: smart contracts facilitate the automatic execution process in transparency, traceability, immutability, decentralization, and privacy. The fusion of 3D printing and Blockchain technologies will enable fast forensic analysis in the event of a part failure. Blockchain allows producing components, resp. use local 3D printers to make parts. Blockchain smart contracts and hashing can be used very effectively for data and process integrity. The benefits include the following [11; 12; 13; 14]:  
* Delivery times are shortened by creating a production scheme with a global network of 3D printers;
* Back-analysis of parts and reduction of pressure on OEM costs;
* Cost reduction for value-added activities;
* More flexible inventory management through digital assets;
* Elimination of transport costs by using digital transfer via the cloud to the place of use;
* Elimination of storage costs, as parts will be stored in a digital warehouse;
* Elimination of duties and charges as objects move digitally across borders;
* Effective form of payment via Bitcoin;
* Setting standards for digital fibres and digital twins;
* Each object will have a certificate of authenticity, which will prevent fake parts from entering supply chains. A very important company in the aerospace industry in connection with the combination of 3D printing and blockchain is the company VeriTX, which in the source [13; 15] presents his own experience in this direction. One of them is the following [13; 15]:  
_\"When an F-15 Eagle fighter needed a metal part, its commanders turned to VeriTX's virtual marketplace, where they were able to find a nearby supplier who could make it on a 3D printer and deliver it in six hours. Using the old printed catalogue system, it would have taken 265 days, on average, to get the jet flying again.\"_  
The importance of Blockchain is generally in the protection and sharing of data related primarily to print licenses, production process data, material origin information, tests and simulations, payment records, and parts certification [14]. In a study by [PERSON], [PERSON], [14] Table 1 contains material that points to the importance of Blockchain in connection with 3D printing. The study defines the potential for business model innovation for local manufacturing, shared factories, and secure design marketplaces well-crafted findings of authors to increase the innovative capacity of business models. The study by [PERSON], [PERSON], ref. [14] also mentions the pitfalls that currently hinder the use of blockchain by companies in practice. These barriers include the development of stakeholder management concepts, corporate cultures that do not support the sharing and development of ecosystems, and regulatory conditions regarding the protection of personal data. At the technical level, the method of linking the physical printing parts and the digital ledger of the blockchain requires further attention.