The need for Unmanned Surface Vessels (USVs) has been continuously growing in recent years due to the increased demand for automated inspection, surveillance and monitoring platforms. This paper proposes a framework for the development of a modularized, low-cost USV, manufactured with the Fused Filament Fabrication (FFF) technology. The vessel can be operated via Radio Control (RC) and is able to operate autonomously as well. The purpose of this platform is mainly safety applications; however, it is possible to utilize it for scientific tasks, such as water quality monitoring and water structure inspection. Its main advantages are summarized in the modular design, the ability to propel by air and the low build cost. The modular design allows for easy assembly of the vessel, as well as enabling a dynamic size change of the hull. It is noted that the vessel is intended for use in relatively calm waters such as lakes, ponds and reservoirs, especially in waters with dense vegetation. Therefore, the propulsion system was designed with these conditions in mind. Regarding the build cost, the combination of 3D printing, hobby-grade hardware and reliable open-source protocols led to the development of a fully operational and efficient safety platform, with a low cost (<EUR 600). Especially when compared to the cost of commercially available USVs, it delivers a high capability/price (C/P) ratio. Finally, the performance of the platform in terms of buoyancy, stability, steering ability and navigational capabilities was validated through field experimentation in the lake Polyfytos in Kozani, Greece.