Face shields have been adopted worldwide as personal protective equipment for healthcare professionals during the COVID-19 pandemic. This device provides a transparent facial physical barrier reducing the exposure to aerosol particles. The fused deposition modeling (FDM) is the most applied process of additive manufacturing due to its usability and low-cost. The injection molding (IM) is the fastest process for mass production. This study is the first to perform a qualitative comparison between the use of FDM and IM processes for mass production and rapid distribution of face shields in a pandemic. The design of the face shield and tests were conducted in prototyping cycles based on requirements of medical, Brazilian standards, manufacturing, and production. The FDM face shields manufacturing was carried out by a volunteer network, and the IM manufacturing was carried out by companies. The volunteers produced 35,000 medical face shields through the FDM process with daily delivery to several hospitals. A total of 80,000 face shields was produced by the IM process and delivered to remote Brazilian regions. The mass production of 115,000 face shields protected health professionals from public hospitals in all states of Brazil. In a pandemic, both FDM and IM processes are suitable for mass production of face shields. Once a committed network of volunteers is formed in strategic regions, the FDM process promotes a fast daily production. The IM process is the best option for large scale production of face shields and delivery to remote areas where access to 3D printing is reduced.