A modular system for blow molding a container. The system may include a first portion, a second portion, and a third portion. The first portion and second portion may each include a shell, a mold removably coupled to the shell, and a top plate. The third portion may include a base and a base mold. The molds may be 3D printed. The molds together may define a blow mold cavity. The modular system may be used at lab scale, pilot scale, or full production scale. The molds may be durable and smooth enough for full production scale. Some embodiments are directed to methods for making a modular system for blow molding a container.