Prosthetic care is often inaccessible in Low and Middle-Income Countries (LMICs) due to limited resources and lack of trained professionals. Additionally, prosthetic sockets are frequently abandoned due to poor fit, discomfort, and inability to accommodate residual limb volume changes. 3D-printing, Computer-Aided Design (CAD), and adjustable prosthetic sockets offer solutions to increase access to prosthetic care in LMICs. This study aims to design an adjustable 3D-printed transradial prosthetic socket, and a simple and robust fitting method tailored for use in LMICs. The focus is on customisation, patient comfort, and ease of production and implementation by local prosthetists. An adjustable 3D-printed transradial prosthetic socket was designed using the ACCREx method to expand the solution space. Concepts were formed through a morphological chart. The final designs were converted into simulation models suited for non-amputees. These models were then fitted, customized, and evaluated. Both objective and subjective data verified and validated the designs, emphasizing functionality, comfort, practicality, and compatibility between the prosthetic socket and fitting method. The prosthetic socket is fully 3D-printed and features proximal-distal rings and a condyle brace with a reversible zip-tie-inspired adjustment mechanism. The fitting method includes a modular fitting model and a (semi-)automated parametric CAD-model. Results indicated sufficient compatibility between the prosthetic socket and fitting method, and a generally perceived correct socket fit. The fitting method enables easy socket customisation, requiring minimal training and active labour. This study offers a proof of concept for an easier, more robust, and less labour-intensive solution for comfortable prosthetic socket customisation, suited for LMICs. The developed 3D-printed prosthetic socket and fitting method represent a significant step towards accessible prosthetic sockets in LMICs and the global democratisation of prosthetic care.