Arduino is certainly the most popular method of getting info electronics, or at least embedded electronics. My BlueStamp Engineering students seem to gravitate to them when selecting their projects. But what about after the first few projects have been created with the Arduino? What if the designer wants to add a relay, or another LED to the board? Most people create a shield which allows them to plug in, but for simple projects I believe there is a better way: creating their own Arduino clone (AKA Derivative). This is where the designer modifies the public Arduino EAGLE PCB files to add their extra parts, and then makes their own board! It can save cost, space, and connectors! I go into more detail on my latest Element14 post:
Derivatives enjoy some significant design benefits over a shield. First, a single board is less than half the size and more robust than stacking an additional PCB on top of the purchased Arduino via headers. Second, it will be a cheaper solution than buying a stock Arduino and the custom shield PCB/parts. Finally, there is a lot to learn from starting with an existing PCB design and tweaking it. Not to mention the pride one would get from creating their own stand-alone design, even if it is attained by standing on the shoulders of giants.