Hybrid prototyping (HP) – the combination of mixed prototyping media within a single product design – has shown potential to substantially reduce process cost and fabrication time. However, previous work has not considered how HP processes and fabrication should be aligned with designer intent or activity needs, how these may change the realised savings or good practice guidance for successful implementation. This work proposes three approaches for HP with Lego and additive manufacturing, targeted towards enabling mixed fidelity for prototype flexibility, parallelisation for rapid fabrication and component reuse to minimise material waste. It then establishes good practice guidance and proposes a HP method that accounts for practical and process constraints, then implemented through an automated hybridisation tool. Approaches are compared through a simulation study and a case study to establish relative benefit. Results show potential time and material savings of 56% and 76%, respectively, depending on the approach chosen, demonstrating the substantial and practical scope for savings that HP provides.