Scaffold-free 3D printing of shells: Introduction to patching grammar

This paper describes the Patching technique for building shells without wasteful support, thanks to 3D Printing technology. The method developed in this paper extends ancient vaulting techniques and decodes and formalises them into a design Grammar. Furthermore, numerical tools such as mesh pattern topology and shape topological skeleton are used to adapt vaulting techniques to 3D Printing data. This Grammar classifies the self-standing interconnected components (Patches) and automatically decomposes the non-traditional shapes into those Patches following the Patching process. As a result, the practitioners can use the Patching technique to fabricate low-cost, efficient shells. The presented prototype demonstrates that the Patching technique can contribute to printing shells with low-strength material such as fresh clay without any scaffolding. However, more research needs to be done on the material design and rheology control, shells' cross-section optimisation, and material failure theories such as Mohr-Coulomb and their application to 3D Printing using earth-based material.