Advances in Additive Manufacturing (AM) techniques have expanded the possibilities to fabricate unique shapes, offering various advantages over traditional manufacturing techniques concerning material efficiency, product customisation and process control. AM using organic materials such as wood has been introduced by the combination with polymers to produce 3D printing filaments. These filaments use groundwood and therefore eliminate long fibres of naturally grown timber, losing its inherent material qualities such as anisotropy and structural performance. This research investigates strategies for a novel AM process using continuous solid wood to fabricate high-resolution material-efficient timber structures based on topology optimization. We examined this novel AM process in three work packages: material production, robotic fibre placement process and a design method through topology optimisation. The developed robotic fabrication process enables the deployment and extrusion of a novel material: a continuous solid wood filament made of willow withies. This process allows for a high degree of geometric freedom to assemble timber to create homogeneous structures at high resolution, providing the aesthetics and structural advantages of wood on a micro-scale and therefore giving entirely new possibilities for timber construction.