A customizable facility for manufacturing at least one product has at least one modular unit in communication with at least one central unit configured to provide utilities to the at least one modular unit. In some embodiments, the central unit(s) and modular unit(s) are positioned at least partially within a shell. Each modular unit can be a fermentation unit, a pre-viral unit, a post-viral unit, a utility space, a warehouse, a media buffer facility, an office, a personnel unit, or another unit. The modular units can be arranged to maximize a number of modular units within the shell while minimizing a footprint of the shell. A method of assembling a facility for manufacturing at least one product includes providing at least one central unit and providing at least one modular unit in communication with the central unit(s) such that utilities are provided by the central unit(s) to the modular unit(s).