Myco-Lock: Enabling Topological Interlocking Assemblies with Mycelium-Based Composites

Topological interlocking assemblies (TIA) are structural systems composed of kinematically interlocking elements that rely solely on friction for stability, eliminating the need for additional connectors and enabling full reversibility. Precision in interlocking interfaces is crucial for effective load transfer. While existing research focuses on durable materials like concrete and 3D-printed polymers, less attention has been given to using biodegradable materials such as mycelium-based composites (MBCs). MBCs offer a sustainable alternative to conventional construction materials but present challenges for reversible assembly due to their non-homogeneous composition and dimensional shrinkage. To address this, we propose a method combining additive manufacturing (AM) with mycelium cultivation. A PLA bioplastic shell infused with wood particles serves as a lost formwork, which is then filled with a mycelium-inoculated substrate. The mycelium consumes the printed shell, naturally bonding the formwork and infill. The result is a lightweight, interlocking module capable of supporting compression loads while offering insulation and acoustic benefits. Given the shrinkage issues affecting interlocking precision, a study was conducted to assess dimensional variations and develop design adjustments. We demonstrate the design, production and cultivation process, as well as shrinkage control strategies. A full-scale prototype partition wall (2.40 x 1.00 m) with 112 interlocking blocks was fabricated using consumer 3D printers. Overall, the study presents a methodology for integrating MBCs in reversible architectural assemblies, enhancing reusability and extending material lifespan.