The use of amorphous microspheres as filler in composites is promising due to their light weight, low cost, incombustibility, and the ability to alter relevant properties of the final composite. Contrary to glass spheres, perlite microspheres are much cheaper and can be tailor-made to facilitate purpose-oriented alteration of the final composite. We report the use of perlite microspheres for the preparation of: (1) composites, through a compression molding (hot pressing) technique; and (2) composite filaments, in a single screw extruder, as well as their use for sample printing through Fused Deposition Modeling (FDM). Proper characterization of the produced composites allows for their evaluation in terms of physical, thermal, and mechanical properties and with regards to the manufacturing technique, the filler fraction, and size. Composite samples of acceptable quality in terms of filler survival and dispersion as well as mechanical properties were produced through compression molding using fine expanded perlite microspheres (<90 μm) up to an infill ratio of 40 vol.%. Fine fillers (<90 μm) performed well in FDM, allowing printing of composite dogbone samples with a higher Young’s modulus and elongation and similar ultimate tensile strength compared to benchmark, up to an infill ratio of 20 vol.%. Composite samples present a slightly lower burning rate compared to those produced solely by ABS. Perlite microspheres present good workability in both applications, possessing satisfactory performance as filler in the composites, and can thus be assumed a promising multifunctional filler for various thermoplastics considering their low price, environmental impact, and fire rating.

Current technology to prevent biofouling usually relies on the use of toxic, biocide-containing materials, which can become a serious threat to marine ecosystems, affecting both targeted and nontargeted organisms. Therefore, the development of broad-spectrum, less toxic antifouling materials is a challenge for researchers; such materials would be quite important in applications like aquaculture. In this respect, surface chemistry, physical properties, durability and attachment scheme can play a vital role in the performance of the materials. In this work, acrylonitrile butadiene styrene (ABS)/micro ZnO or nano ZnO composite lattices with different metal oxide contents were developed using 3D printing. Their antifouling behavior was examined with respect to aquaculture applications by monitoring growth on them of the diatoms Navicula sp. and the monocellular algae Chlorella sp. with image analysis techniques. As shown, the presence of metal oxides in the composite materials can bring about antifouling ability at particular concentrations. The present study showed promising results, but further improvements are needed.

Photocatalysis is a powerful advanced oxidation process for water remediation, yet benchmarking has disproportionately relied on model organic dye pollutants under idealized conditions—overstating practical performance and obscuring mechanistic complexity. Three-dimensional (3D) printing now offers an unprecedented opportunity to engineer photocatalytic reactors with precisely controlled architectures, optimized mass transfer, tunable porosity, and defined light-penetration channels—capabilities unattainable with conventional slurry or thin-film configurations. This systematic and critical review examines the state of the art in additive manufacturing of photocatalytic reactors for water treatment, focusing on three under-developed dimensions: (i) performance validation against environmentally relevant contaminants—pharmaceuticals, endocrine-disrupting compounds (EDCs), PFAS, microplastics, and waterborne pathogens; (ii) mechanistic rigor, including reactive oxygen species (ROS) identification, quantum yield determination, and mineralization metrics; and (iii) genuine reusability under realistic cycling conditions. The dominant printing modalities—FDM/FFF, SLA, DLP, DIW, and binder jetting—are critically evaluated for photocatalyst loading, geometric resolution, and scalability. A persistent gap is identified between proof-of-concept studies and systems capable of rigorous quantitative benchmarking. To address this, a minimum reporting standard is proposed, and the materials, engineering, and regulatory challenges that must be resolved before 3D-printed photocatalytic reactors can transition from academic novelties to deployable treatment units are outlined. A total of nine peer-reviewed studies, identified through a systematic search of Scopus and Web of Science (2016–2026), form the evidence base for the quantitative assessments reported herein. Screening and data extraction were performed by a single reviewer (G.K.) without independent verification, which represents a limitation of the review.