National Fab Lab Network Act of 2021 This bill establishes the National Fab Lab Network as a nonprofit corporation. A fab lab is a digital fabrication facility with the capabilities necessary to create form and function from digital designs. The bill requires the National Fab Lab Network to (1) endeavor to establish at least one fab lab in each congressional district and additional labs according to local demand, (2) link fab labs into a national network and promote their further expansion across the country, (3) serve as a training and operating resource for fab labs and their leaders and mentors, (4) maintain a national registry of fab labs, (5) provide standards and protocols for connecting fab labs, and (6) assist fab labs in producing fab labs.