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This paper explores the evolution of fibrous enhancements in labyrinthine acoustic metamaterials, transitioning from stochastic fibrous fillers to programmable 3D-printed infill. While previous studies demonstrated that manual packing of natural fibres (e.g., dried dill) into labyrinthine slits significantly enhances low-frequency absorption, it suffers from manufacturing difficulties and uncertain reproducibility. Moreover, due to the uneven and random fibre distribution, analytical modelling may be inaccurate and require complex modifications. To address these limitations, we propose the use of Fused Deposition Modelling (FDM) to integrate controlled fibre networks directly into the channels. A comparative study is presented between a bio-filler reference and an engineered Cross-ply (CP) infill pattern. Experimental results from impedance tube measurements reveal a significant advantage of the engineered 30% CP infill over stochastic natural fibres. While the bio-filler achieves absorption at lower frequencies, the 3D-printed infill generates a significantly broader and higher absorption peak at 1050 Hz, reaching nearly perfect absorption. Consequently, the absorption curve of the fully 3D-printed sample exhibits a broader bandwidth and a higher maximum absorption coefficient than the curve obtained for the bio-filler composite. This demonstrates enhanced broadband sound absorption combined with high manufacturing predictability. This work establishes a digital framework for the design of sub-wavelength absorbers with tunable, reproducible dissipation mechanisms.