Three-dimensional printing (3DP) represents a significant innovation in the construction sector, offering substantial benefits in terms of efficiency, customisation, and sustainability. In the context of built heritage rehabilitation, it is capable of accurately reproducing architectural elements, facilitating conservation efforts, while minimising waste and resource consumption. However, in this field, ensuring material compatibility with original structures is essential. This study explores the development and optimisation of lime and cement-based mortars for 3DP applications, focusing on their physical and mechanical performances (on moulded specimens) for use in replicating elements of a renowned Portuguese theatre. Laboratory testing supports the selection of suitable mortar compositions, aiming to balance performance and fidelity to historical construction practices. This research seeks to contribute to explore the potential of 3DP for heritage conservation, promoting innovative, durable, and culturally sensitive restoration strategies.