Download: ArduinoShieldScaffold.zip

Last year I made a pair of simple Eagle CAD files that contained headers and board outlines for an Arduino shield. The idea was that you could create a new project, copy the scaffold .sch and .brd files into it, then rename them and begin designing your new shield project. There are several part libraries out there with Arduino layouts, but in order to change the board outline, text, or add/remove holes, you'd have to go into the library and edit the part. And you'd actually need to make a new part, because if you ever open a different project and update the libraries, your edited part would overwrite whatever you had before.

Anyway, I updated the Shield Scaffold to be a little more useful. The TallParts layer contains outlines of the USB connector, power connector, and ISP header. You want to avoid any pins or exposed copper in this area, otherwise you may have an accidental short. The ArduinoHoles layer contains the original hole locations and diameters on the Arduino, in case you want to duplicate those holes to mount the shield securely with screws.

When you're ready to generate Gerber files, just make sure the TallParts and ArduinoHoles layers aren't selected in any of the CAM layers.