Nowadays, enormous efforts are being made to improve the durability and sustainability of structures. Among these, concrete shells represent a unique category, typically characterised as thin and slender elements that fulfil both aesthetic and efficiency requirements. However, this design approach often conflicts with the need to provide sufficient concrete cover for steel reinforcement, which is essential to prevent corrosion and ensure long-term durability. As a result, the prevalence of concrete shells has diminished, leading to a reduction in innovative architectural solutions and structural effectiveness. This paper introduces a method for the structural design of concrete shells that are reinforced with fibre-reinforced polymer (FRP) bars. The algorithm, developed in Python, is designed to be adaptable for various shell types by accounting for both membrane and flexural actions, and it is based on equilibrium conditions for the limited ultimate state of the reinforcement and cracked concrete. The strain compatibility condition has also been integrated to ensure a compression-controlled failure mode, and the optimisation algorithm has demonstrated efficiency. The Python code has been uniquely developed to address convergency issues and enable the design for any loading scenario. The proposed method is general enough to allow the strategic position of the reinforcement along a specific direction to minimise the tensile forces that the reinforcements must resist. Hence, it is suitable for use in a concrete shell optimisation procedure.