To achieve true circularity, load-bearing glass structures need joinery systems that not only meet structural and aesthetic performance criteria but also support disassembly and recycling. An iterative design approach was employed, starting with a comprehensive literature review of structural glass connections and proceeds through hands-on material trials. In adhesion experiments, polymers commonly used in Additive Manufacturing (AM) were evaluated for their warping, manufacturability and bond strength on glass substrates. Building on these insights, an iterative geometry optimisation phase refined a snap-fit interlocking design. This design was then mechanically tested and validated through a case study and prototype. Key findings include the selection of PLA as a pragmatic interlayer material, balancing printability, minimal thermal warping, and sufficient stiffness, despite its low glass transition temperature (60 °C) and biodegradability.

The resulting elastic averaging interlock is manufacturable (1 mm nozzle), resists thermal distortion, and self-aligns under preload. Mechanical validation of this interlock involved custom shear and compression tests, which demonstrated peak force transmission between Fshear = 1.77 kN and 6.13 kN under a starting preload of Fnormal = 500 N. These forces correspond to effective friction coefficients of approximately mu = 1.060, exceeding typical friction values specified in Eurocode. An architectural case study of a compressive-only glass vault confirmed that service-level compressive stresses and wind-induced lateral loads remain within safe limits while allowing damage-free disassembly.

A robotic, non-planar AM workflow was developed to create a 1:2 interlayer prototype on osteomorphic shaped cast glass bricks. Using a 5-axis slicer and a UR5 robotic arm in combination with a custom extrusion end-effector and an Arduino microcontroller, the designed interlayers were AM but leave room for optimisation. This prototype showcased the adaptability of the approach to custom and complex geometries. Finally, heat-softening of the PLA interlayers enables clean separation and full material recovery, supporting a truly circular lifecycle for both glass and polymer components.

This proof-of-concept paves the way for scalable production of polymer interlayers for structural glass applications. It demonstrates that AM can play an important role in enabling reversible, high-performance structural glass assemblies, bringing circular construction one step closer.