In the last three decades, an increasing number of man-made marine hard defence structures have been built as a rapid and cost-effective means of coastal protection. The idea of integrating ecological principles into urban infrastructures is relatively new and challenging. Using coastal structures to host endangered species holds a significant promise for biodiversity conservation in coastal cities worldwide. Nevertheless, marine infrastructures provide unconventional substrates for benthic communities due to a lack of surface complexity, orientation, exposure, structure, and texture, affecting the recruitment, survival, and growth of organisms. Additionally, most of the approaches are limited to the implementation of bare substrates, although specifically designed for enhancing biodiversity through settlement facilitation. This study presents a preliminary investigation into the development of bio-compatible units specifically designed to restore macroalgal forests, i.e. Ericaria amentacea habitats, implementing the ex-situ outplanting (therefore positioning in the field vegetated substrates) in the Ligurian region (Northwestern Mediterranean Sea), performing an actual forestion of artificial coastal infrastructures, enhancing their ecological value. The research evaluates various designs and material formulations of cantilever prototypes for their ability to support algal settlement and growth and resist hydrodynamic forces once deployed on the artificial reef. Laboratory tests have been performed to assess mechanical properties, including flexural and compressive strength, density, as well as the water absorption of the restoration structures. Laboratory cultures explored different material performances in promoting algal growth. Preliminary field evaluations under wave action highlight investigated performance in durability and compatibility within marine environments. Aligning with the EU Nature Restoration Regulation requirements, our study is a step forward to the development of innovative, nature-based solutions for mitigating anthropogenic impacts due to the establishment of artificial infrastructures at sea.