3D-printed flexible endoscope and 4-mm directional forceps: Affordable prototypes for expanding minimally invasive surgical training

Articulated endoscopic instruments can enhance dexterity within constrained workspaces; however, their complexity and cost limit accessibility for training, prototyping, and early-stage evaluation. Additive manufacturing offers a practical approach for developing mechanically functional, low-cost articulated devices for engineering exploration and simulation-oriented applications. This study describes the mechanical design, bench-top characterization, and preliminary proof-of-concept assessment of two additively manufactured, cable-driven endoscopic prototypes: a flexible endoscope with an integrated working channel and bidirectional distal articulation, and a 4-mm steerable surgical forceps with independent jaw actuation. Both devices were fabricated using fused deposition modeling. Bench-top experiments quantified distal deflection, motion repeatability, force-related behavior, simulated task execution, and user perception. The flexible endoscope achieved effective distal deflections of 178° ± 2° vertically and 171° ± 3° horizontally while maintaining compatibility with standard 2.8-mm endoscopic instruments. During cyclic testing, it demonstrated sub-centimeter positional consistency after 1000 articulation cycles, with 95th percentile errors below 8 mm in both directions. The steerable forceps exhibited a geometric articulation range of 180°, an effective distal deflection of 85° ± 2°, and repeatable tip motion over 500 cycles, with a mean positional error of 0.26 mm. Simulated tasks were completed with high user perception scores for both prototypes. Fabrication costs were USD 166.49 for the endoscope and USD 27.75 for the forceps. These findings suggest that cable-driven architectures combined with additive manufacturing can reproduce key kinematic principles of articulated endoscopic instruments using low-cost fabrication methods. The prototypes should be interpreted as early-stage engineering demonstrators rather than clinically deployable devices.