Building on a large scale with Additive Manufacturing (AM) is one of the biggest manufacturing challenges of our time. In the last decade, the proliferation of 3D printing has allowed architects and engineers to imagine and develop constructions that can be produced additively. However, questions about the convenience of using this technology, and whether additive large-scale constructions can be feasible, efficient and sustainable are still open. In this research 3D printing is considered not as a question, but as an answer to the increasing scarcity of material resources in the construction industry. This paper illustrates the overarching process from concept to the realisation of the Trabeculae Pavilion, a load-responsive architecture that is entirely designed and optimized for 3D printing, using Fused Filament Fabrication (FFF) - one of the most cost-effective additive techniques of production. The research methodology is based on a multi-scale computational workflow that integrates several aspects, such as material testing, bio-inspired design algorithms, multi-criteria optimization, and production management. The work culminates in the construction process of a full-scale architectural prototype; an anticlastic shell that features a cellular structure with increased material and structural efficiency.