GIPPO: A Graph-based, Iterative, Printing-Path Optimization Slicer for Architected Lattices

Architected materials of significant geometric complexity offer exceptional mechanical properties that often surpass those of their constituent materials. However, their fabrication through extrusion-based 3D printing remains hindered by suboptimal printing trajectories, which is inherent to commercial slicing software. They produce multiple non-continuous paths that compromise fabrication time, shape fidelity, and structural integrity, particularly for thin-walled lattice structures. To address this issue, we introduce GIPPO (Graph-based, Iterative, Printing-Path Optimization), an open-source slicing platform that transforms complex lattice designs into optimized printing trajectories. Lattices are converted to graph networks to derive the optimal printing trajectories through a modified version of Prim's algorithm. The resulting paths are translated back to Euclidean coordinates and exported as a ready-to-use G-code. We validated GIPPO's performance against conventional slicing software across six architected lattice geometries fabricated from thermoplastic polyurethane using fused deposition modeling. GIPPO-optimized constructs demonstrated superior shape fidelity with reduced local thickness deviations, no missing struts, and minimized excess material deposition compared to conventionally printed controls. Mechanical testing revealed that printing path optimization directly influences both uniaxial and out-of-plane mechanical responses, with different optimization strategies yielding distinct performance characteristics suited to specific loading conditions. Moreover, the platform accommodates both planar and non-planar printing geometries and enables fabrication of objects with varying infill patterns per layer. Our work addresses critical limitations in commercial slicing software and opens new opportunities for high-fidelity fabrication of complex architected materials.