## 4 Discussion  
With the rapid development of CAD, 3D scanning, and 3D printer capabilities, applications in the field of 3D-printed rehabilitation devices have a tremendous potential [11]. Moreover, 3D printing allows you to establish assistive orthopedic devices that are more cost-effective and durable, lighter, and easier to replace than conventional braces [12]. In this study, customized 3D-printed writing and typing assistive devices were shown to improve the quality of life of patients during writing and typing tasks. The current study showed that patients who could not write were able to do so, and their accuracy and speed improved. Our results also showed time delays in the examination after the use of assistive device, although we considered this to have resulted from low proficiency. Regardless of the outcomes, all patients had a high subjective satisfaction, which led to psychiatric stress relief and ADL improvement. Thus, the device was effective in improving the quality of life. Assistive devices created using 3D printing technology has several advantages. Figure 3: **(A)** Patient 1 wearing the fourth three-dimensional (3D)-printed writing integration device made of silicone material. **(B)** Patient 2 wearing the 3D-printed typing and writing integration device made of silicone material. **(C)** Patient 3 wearing the fourth 3D-printed typing and writing integration device made of silicone material. **(D)** Patient 3 wearing the 3D-printed typing integration device with the polylactic acid material. Among them, the most significant is that these devices can be easily transformed for specific purposes based on basic hand shapes using stored 3D image files. Although it was not explained in detail, different plastic hand aids were developed according to the basic hand forms. Then, they were applied to the three patients. However, the use of these devices was not successful due to poor utilization and patient satisfaction. Hence, the silicon writing and typing device made from a 3D-printed frame was established, and the thickness and length of each patient's hand were measured to make the device more suitable for each patient. Device cost is a hindrance for the application of devices in patients with severe disability who require orthosis. Nonetheless, [PERSON] et al. developed soft robotics prosthetic hands with a relatively low price at 200 USD. However, this does not include the quick disconnect wrist [13]. Therefore, we developed a low-cost and lightweight 3D-printed hand assistive device using a simple design. Therefore, the patient's compliance would be higher, which might play an important role in improving function. To help more patients with physical disabilities, low-cost and simple assistive devices are essential in the rehabilitation field. Hence, these 3D-printed products may be cost-effective, and their use as an alternative to conventional devices is promising. The current study had several limitations. Patients were taught how to use the writing and typing device. However, they were not trained. Then, they were evaluated after self-use. Moreover, only three patients were included in the study, and long-term follow-up was not performed. Although the long-term usability of devices was not assessed, users could benefit more from orthosis if they had a sufficient training time to adapt to it. Nevertheless, further research should be performed to investigate the feasibility of this technology as it might be an alternative to the conventional orthosis in patients with cervical SCI. Finally, this study did not objectively evaluate patient satisfaction. Hence, future research should include an objective evaluation of satisfaction in addition to improved performance. Conceptualization, J.H.K. and H.S.Y. ; Data curation, J.H.K. and Y.K.L. ; Formal analysis, J.H.K. ; Investigation, S.H.H. and B.M.L. ; Methodology: H.S.Y. ; Project administration: H.S.Y. ; Resources: H.S.Y. ; Software: W.S.S., G.S.P., S.B.N.L. and M.J.; Writing--original draft preparation, J.H.K. ; Writing--review and editing, H.S.Y.