Introduction: Phocomelia is a rare congenital illness that occurs at birth due to an inherited genetic disease or the thalidomide teratogenic impact. The patient had tetra-phocomelia, which caused her upper and lower limbs to shorten, making it difficult for her to write correctly. Thus, this project aims to develop an assistive device that will assist the patient in writing independently. Methods: Patient assessment, device design and analysis, and fabrication with 3D printing technology were all part of the product development process. The anatomical shape of the patient’s limb was captured using a 3D scanner, and the socket design was sketched using the information. The different thicknesses of the socket were analyzed using finite element analysis to evaluate the product design. The device was then printed using the best parameter setting available. Results: The socket was designed in response to the demands and requests of the patient. One of the unique features was adjusting the fitment of a pen at various rotations and linear motion angles. The thickness of 3.0mm was found to be sufficient for printing the socket by computational analysis. Following that, the printed socket was delivered to the respective patient. During the device’s functional evaluation, the patient demonstrated the ability to write her name clearly within 1 minute of recorded time with good readability. Conclusion: The finalized design of the socket was successfully analyzed and found to be safe. The patient fitted the socket well and was capable of writing appropriately, using the developed adaptive device.