This thesis presents a product development process, where an existing solution on a cab door have been analysed and developed, with the aim to result in a cost-effective concept solution for handling tolerances on the door frame. The methodological approach in this thesis is based on Volvo Construction Equipment’s development model; The Global Development Process, which started with a pre-study phase where the problem formulation was established. The problem formulation in short is to find a solution for how to handle narrow tolerances in steel profiles for the door weldment on cab doors. Various solution ideas were discussed and concepts were generated with focus to design a new cab door corner that would solve the problems addressed by the project. The applied method resulted in a final concept consisting of the same steel profiles but with new dimensions, and two new concepts in each corner; one corner module that is placed inside the steel profiles and joined by welding, and a plastic shell that covers the welded corner. The concept was validated using a prototype of the proposed solution, where tests show that the requirements were achieved, besides a few deficiencies. A cost comparison between the existing and the proposed solution was made within limitations for this thesis. The result of the cost comparison shows an indication of that the proposed solution can be more cost-effective than the existing solution. Some of the recommendations after have completing the project are to make a complete cost comparison to ensure that the indication is correct and to analyse the new components to optimize and define the dimensions of them.