First step in making a arduino shield is thinking of what you want it to be. depending on what your shield is going to be will vary the parts that you will need for it.
PS: the picture is a sneek peek on my new arduino shield. :)
Step 1: Designing
We will be designing the shield in a software called eagle.cad. If you don’t have the software already downloaded then here is a link to the website http://www.cadsoftusa.com/ .
In eagle.cad you first design your shield with a schematics. If you don’t know what a schematics is there is a really good video on it by Collin http://www.youtube.com/watch?v=9cps7Q_IrX0 . I use sparkfuns eagle library for the arduino shield. https://github.com/sparkfun/SparkFun-Eagle-Library .
Ones you have that all done you can start making your schematics in eagle.cad. To add a part in eagle.cad you click on the button on the left that looks like a plug and should say add if you hover over it. Then find your component and make your schematics. After you have completed your schematics you have to press the board it is located on the top row of buttons and to the right of the button that looks like film. After you press that another window should pop up and you should see your components. Just move your components were you want them on the shield, there should be thin yellow lines on the points of your components don’t worry that’s what it should have. Once you have your parts where you want them you can ether press auto button it’s the one that’s on the side bar right above the very bottom that looks like a magnifying glass. Or you can press the rout button and hand rout the joints, this is better if you want to only have a 1 sided board.
Step 2: Checking
And read from the part that says Create gerber files and down.