<p>Interconnected porous aluminum monoliths with precisely tailored open porosity were fabricated via fused filament fabrication (FFF) of high-loading Al/ABS composites compatibilized with 2.9 wt.% maleic anhydride-grafted ABS (ABS-g-MA). Filaments containing 77.67 wt.% aluminum powder (average particle size 10–15 μm) were extruded at 200–220 °C and printed into complex geometries using a desktop FFF printer. Thermal debinding at 400 °C (&gt; 98% binder removal) followed by solid-state sintering at 600 °C produced crack-free metallic structures exhibiting 22–28% (mean 25.4 ± 1.2%) open interconnected porosity with a median pore-throat diameter of 6.1 ± 0.4 μm. The optimized compatibilizer concentration increased filament impact toughness threefold, enabling uniform Al dispersion (&lt; 5% voids by SEM) and preventing delamination during post-processing. Fully sintered specimens displayed an engineering tensile modulus of 18.5 ± 1.1 MPa, 0.2% offset yield strength of 24.2 ± 0.9 MPa, and strain at break of 1.4 ± 0.1%, providing an excellent balance between mechanical integrity and high permeability (~ 520–610 L m⁻² h⁻¹ bar⁻¹) for flow-through applications such as catalyst supports and filtration media. Complementary DFT calculations (UHF-B3LYP/6-31G*) on a representative Al₄/ABS-g-(COO⁻)₂ cluster model revealed strongly exothermic bidentate carboxylate coordination (–52 to –68 kJ mol⁻¹) and narrowing of the HOMO–LUMO gap to 3.0 eV, rationalizing the enhanced interfacial adhesion and structural stability. Compared with conventional CNC machining or casting, this low-cost, design-flexible FFF route reduces production time by ~ 70% and energy consumption by 35–50% while achieving 90–95% material utilization. The presented methodology establishes a scalable, sustainable platform for functional porous metallic components in environmental and energy applications.</p>