Multi-ttach: Techniques to Enhance Multi-material Attachments in Low-cost FDM 3D Printing

Recent advances in low-cost FDM 3D printing and a range of commercially available materials have enabled integrating different properties into a single object such as flexibility and conductivity, assisting fabrication of a wide variety of interactive devices through multi-material printing. Mechanically different materials such as rigid and flexible filament, however, display issues when adhering to each other making the object vulnerable to coming apart. In this work, we propose Multi-ttach, a low-cost technique to increase the adhesion between different materials utilizing various 3D printing parameters with three specialized geometric structures : (1) bead and (2) lattice structures that interlock layers in vertical material arrangement, and (3) stitching in horizontal material arrangement. We approach this by modifying the geometry of the interface layer at the G-code level and using processing parameters. We validate the result through mechanical testing using off-the-shelf materials and desktop printers and demonstrate the applicability through a range of existing applications that tackle the benefit of multi-material FDM 3D printing.