Abstract The bottom-up van der Waals (vdW) assembly of quantum materials from low-dimensional building blocks provides a flexible and structurally defined route for designing materials with tailored quantum properties. While stacking two-dimensional (2D) vdW materials has yielded highly tunable platforms for emergent topological and correlated phenomena and has opened pathways toward three-dimensional (3D) layered architectures with extensive lateral design flexibility, the bottom-up vdW assembly of other low-dimensional materials remains largely unexplored. Here, we propose an atomic-scale Lego construction strategy that assembles 2D materials from 1D nanoribbons, embedding design freedom at the structural level through atomic-scale control over lattice geometry, stacking, and edge configuration. Using graphene nanoribbons (GNRs) as a prototype, we develop a general weaving approach that interlaces flat or curved ribbons into stable, periodic 2D networks-analogous to stacking 2D sheets into 3D crystals, but instead progressing from 1D elements to 2D architectures. The resulting woven GNRs (w-GNRs) exhibit geometry-dependent electronic behavior: ribbon width determines the band gap, while inter-ribbon spacing controls the bandwidth and leads to flat-band formation near the Fermi level. By weaving curved ribbons, we construct kagome and square lattice configurations that host symmetry-protected flat bands and orbital degeneracies. This atomic Lego framework enables scalable construction of artificial 2D materials from 1D components, expanding the design space for highly tunable 2D systems with emergent quantum properties.