As demographic growth and climate change effects increase, agriculture intensifies its pressure on the natural ecosystems from which life on Earth depends. In recent years, novel designs and resource-efficient manufacturing methods have been studied to alleviate the impact of food production, many of them incorporating farms into the urban context. However, farming in freshwater bodies remains largely unexplored and constitutes a great opportunity for innovation when land is scarce. Physical requirements for floating farming demand water barrier, solid, inert, and food-grade material with sufficient natural light transmittance, and lightweight, large-scale, complex-shaped components. Therefore, Polyethylene Terephthalate (PET) is presented in this paper as an ideal material for the fabrication of deployable floating farm modules, and Fused Deposition Modeling (FDM) is selected as the most appropriate manufacturing process for the required geometries. Today, recycled polymers in 3D Printing have progressed as a more sustainable feed for small-scale applications. However, there are limited built examples of Additive Manufacturing (AM) using recycled polymers in large-scale real-life applications. This project explores digital designs and fabrication approaches to large-scale manufacturing using PET obtained from single-use bottles to produce empirical prototypes tested in real-life conditions. The research prompted the digital design of a one-meter diameter translucent dome and a flotation platform, their fabrication using large-scale FDM, the assembly of the printed elements, and the monitoring of the farming module performance during operation. The paper covers the state of the art of related 3D printing technologies and their application in food production devices, details the design process of the floating module, explains the selected printing processes and interfacing strategies, and discusses the empirical evidence on the benefits and drawbacks of large-scale AM applied to the cultivation of food. Overall, the research demonstrates the possibilities of 3d Printing using recycled polymers, adding novel insights from a fully-functional project to the incipient body of research on digital manufacturing in food production.