Three-dimensional (3D) printing of polymer materials encompasses a wide range of applications and innovations. Polymer-based 3D printing, also known as additive manufacturing, has gained significant attention due to its versatility, cost-effectiveness, and potential to revolutionize various industries. The current paper focuses on obtaining a durable low-cost rehabilitation knee orthosis. Researchers propose that the entire structure should be obtained using modern equipment within the additive manufacturing domain—3D printing. The researchers focus on determining, through a 3D analysis of the entire 3D model assembly, which parts present a high degree of stress when a kinematic simulation is developed. The entire 3D model of the orthosis starts based on the result obtained from a 3D scanning of the knee joint of a patient, providing a precise fixation, and allowing for direct personalization. Based on the results and identification of the critical parts, there will be used different materials and a combination of 3D printing strategies to validate the physical model of the entire orthosis. For the manufacturing process, the researchers use two types of low-cost fused filament fabrication (FFF), which are easy to find on the worldwide market. The motivation for manufacturing the entire assembly using 3D printing techniques is the short time in which complex shapes can be obtained, which is relevant for the present study. The main purpose of the present research is to advance orthotic technology by developing an innovative knee brace made of 3D-printed polymers that are designed to be lightweight, easy-to-use, and provide comfort and functionality to patients during the rehabilitation process.

The present study focuses on an up-to-date topic regarding flying equipment identified within the category of drones that use, for propulsion and air movements, the power generated by electric motors. In this paper, researchers focus on implementing bladeless technology to calculate, develop, and construct flying equipment known in the literature as drones. The entire structure of the prototype, all the needed parts, is to be obtained using additive manufacturing technologies, which assumes practical realization using 3D-printing equipment. Nowadays, the 3D-printing process has been proven to be a reliable solution when it comes to manufacturing complex shape parts in quite a short time and with reduced costs. The practical study within the present research aims to obtain polymer-based, lightweight parts with complex shapes inside to be implemented in the propulsion of a drone. The complex surface geometry of the parts that this research used is influenced by the ventilation technology offered by the “Air Multiplier” technology. The entire structure of the final drone equipment, all the parts, is to be manufactured using fused filament fabrication (FFF). The main purpose of the fusion is to use the advantages offered by this technology in drones to obtain advantages such as augmented values of thrust, a more agreeable and muffled sound signature, or an increased level of safety.

Following the rising popularity of Unmanned Aerial Vehicles (UAVs) among large-scale users, in the form of domestic as well as professional drones, with applications in domains such as safety (e.g., surveillance drones), terrain mapping (using geo-scanning UAVs), videography drones, and high performance drones used in FPV (First Person View) drone competitions—as well as the rising wide accessibility of Fused Filament Fabrication (FFF)—especially considering the recent apparition and popularization of 3D printers capable of displaying exponential increases in performance metrics, the present work takes into consideration the practice of fabricating UAV propellers by means of FFF, focusing on the theoretical, as well as on the practical aspects of the roughness and quality observed at the level of the resulting surfaces. The paper proposes a set of propeller configurations obtained by combining popular propeller geometries, such as the Gemfan 51466-3 three-bladed propeller and the novel Toroidal propeller model, with a range of different fabrication materials, such as the Polyethylene Terephthalate Glycol (PETG) filament and the Polylactic Acid (PLA) filament. The main aim of the study is to reveal observations on the influence that the surface quality has on the performance metrics of a propeller. Based on the practical work, which aims to develop a comparative study between two drone propeller geometries manufactured by a nonconventional process, 3D printing, the practical applications in the study were carried out using low-cost equipment in order to evaluate the results obtained in a domestic setting. The study involves the identification of the noise values produced by the two geometries due to the roughness of the propeller surfaces.

Laser Powder Bed Fusion (LPBF) enables the fabrication of complex titanium alloy components with high geometric freedom; however, surface integrity and tribological performance remain critical limitations for sliding-contact applications in biomedical and aerospace systems. In this study, the influence of in-layer laser remelting on the microstructure, surface topography, and dry sliding tribological behavior of LPBF-fabricated Ti-6Al-4V ELI (Grade 23) is systematically investigated. Disc-shaped specimens were produced using single-scan (SS) and double-scan (DS, in-layer remelting) strategies and tested in ball-on-disc configuration against AISI 52100 steel at a constant normal load of 10 N and three sliding speeds of 0.10, 0.15, and 0.20 m·s⁻¹. Microstructural and phase-related characteristics were analyzed by X-ray diffraction combined with Rietveld refinement and Warren–Averbach analysis, revealing that the DS strategy increases retained β-phase fraction (up to 5.2%) and promotes crystallite coarsening relative to the SS condition, without significantly altering bulk hardness. Surface morphology examined by SEM/EDS and AFM revealed a more homogeneous near-surface topography in the DS condition. Tribological results indicate that sliding speed governs steady-state friction and wear, with specific wear rates increasing progressively from 5.13 to 5.44 × 10⁻⁴ mm³·N⁻¹·m⁻¹ for SS and from 6.47 to 7.52 × 10⁻⁴ mm³·N⁻¹·m⁻¹ for DS across the investigated speed range. The DS specimens exhibited higher wear rates than the SS condition across all tested speeds, while steady-state COF values remained comparable between strategies, indicating that remelting-induced microstructural modifications affect material removal mechanisms without proportionally destabilizing the frictional regime. These findings suggest that in-layer laser remelting represents a process-integrated parameter with measurable consequences for surface integrity and tribological performance, though the generalizability of these results warrants validation across broader experimental conditions.