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In this study, we developed and preliminarily evaluated a low-cost, lightweight, portable hip\u2013knee exoskeleton prototype capable of generating controlled hip and knee joint motion for rehabilitation-oriented range-of-motion training. The prototype was constructed mainly of 3D-printed polylactic acid parts and powered by a pair of high-torque servo motors in the hip and knee joints. A Bluetooth-connected Android app was programmed to offer two modes: rehabilitation mode for independent joint control and a gait-inspired sinusoidal mode that generates coordinated hip and knee joint trajectories. The cost of the materials used to construct the prototype is estimated to be USD 155 with a weight of about 2.1 kg. Joint motion performance was assessed through time-angle measurements at three predefined speed settings. The hip joint (approximately 60\u00b0 movement) was achieved in 2.2, 1.6, and 1.1 s and the knee joint (approximately 140\u00b0 movement) was achieved in 3.0, 2.0, and 0.6 s for slow, medium and fast modes, respectively. The trial-to-trial variation in commanded servo position remained below \u00b11\u00b0 under the tested conditions. The results demonstrate the feasibility of generating repeatable commanded hip and knee joint motion under controlled laboratory conditions. However, further investigations involving quantitative load-bearing evaluation, safety assessment, user studies, and clinical trials are required before the system can be considered for practical rehabilitation applications.<\/jats:p>","DOI":"10.1177\/20556683261474539","type":"journal-article","created":{"date-parts":[[2026,7,30]],"date-time":"2026-07-30T17:49:56Z","timestamp":1785433796000},"update-policy":"https:\/\/doi.org\/10.1177\/sage-journals-update-policy","source":"Crossref","is-referenced-by-count":0,"title":["Design and preliminary bench-level validation of a low-cost 3D-printed hip\u2013knee exoskeleton for lower-limb rehabilitation training"],"prefix":"10.1177","volume":"13","author":[{"given":"Md. 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