A total of 40 patients with Colles fracture were enrolled in a randomized controlled trial to compare the clinical efficacy of instant 3D printed casts versus polymer orthosis. The participants were randomly assigned to an observation group (treated with instant 3D printed cast; n=20) and a control group (treated with polymer orthosis; n=20). Both groups underwent manual reduction and external fixation. Outcome measures, including visual analogue scale (VAS), immobilization effectiveness and satisfaction scores, Disability of the Arm, Shoulder, and Hand (DASH) scores, complications, and imaging data, were assessed at various time points (before immobilization, 2, 6, and 12 weeks after the fracture). The results revealed that the VAS at 2 weeks, immobilization effectiveness and satisfaction scores at 6 weeks, and DASH scores at 2 and 6 weeks were significantly favorable in the observation group compared to the control group. The study concludes that both treatments are effective, but the instant 3D printed cast outperforms polymer orthosis in various clinical aspects, emphasizing its potential superiority in Colles fracture management.