The advantages of this design are that you don't need to remove the motherboard, cut out a large hole carefully and accurately from the GP2x case, remove (desolder) the existing joystick, build housing to accommodate a rubber pad, use a solder pen tracer to solder wires to the PCB for the D-pad or make the PCB fit correctly in the GP2x. My solution is designed for people like me without good soldering skills, without specialist tools (Dremmel, solder tracer pen, desolder material, etc), who are a bit scared of opening up the GP2x properly (ie over and above removal of back cover!); who want a solution they can make potentially for no cost, easy to make and assemble, and is reliable. You also don't need a PCB converter board with this solution.
Full Article