Fragmented disinfection systems in public spaces reduce prevention effectiveness and increase transmission risk. This research presents a comprehensive design and validation study of a lightweight, modular device casing for multifunctional disinfection and monitoring, combining Prince2 governance with iterative Human-Centered Design and rapid prototyping. Four design variants were developed between 2021–2023, with Version 4 selected for detailed evaluation. The ultra-lightweight stainless steel laser-cut frame ensures accessibility across diverse users: wheelchair users, children, and adults across the 10th–90th anthropometric percentiles per ISO 7250-1:2017. Finite Element Method analyses confirmed structural robustness: under impact loading (400 N), von Mises stress reached 110 MPa with 2.5 mm deformation - well below critical thresholds. Wind load analysis demonstrated exceptional resilience across typical (40 MPa) and extreme hurricane-force conditions (128 MPa at 35.8 m/s). Full-scale ergonomic studies verified comfortable accessibility for wheelchair users across aperture heights of 73.5–98.5 cm. The ballast foundation employs glass fiber-reinforced concrete (GRC), eliminating site preparation while providing exceptional durability and fire resistance (DIN class A1). Rapid service access to critical components prioritizes maintenance during high-risk epidemiological periods. This research demonstrates that designing a modular casing system for a multifunctional device, based on a hybrid methodological approach and aligned with universal design standards and structural resistance requirements, provides an effective research and design direction for disinfection devices in the public health sector.