I'm trying to design a custom shield for a MEGA2560. Without going into details, I'm trying to make a number of power measurements and log everything to either a computer via serial or a locally mounted SD Card. I'm trying to find a good schematic/layout of a basic MEGA shield, essentially the board dimensions and headers. Unfortunately this is not a "Non-Profit" project, so I don't think I can use Eagle, instead I'm trying to use ExpressPCB at the moment. Has anyone released a basic MEGA shield for ExpressPCB? If not, what would be the best way to create my own? I'm guessing I'd need to install Eagle and copy down all of the measurements myself and design my own template in ExpressPCB? Alternatively, is there a better program to be using? I'm not willing to pay for anything just yet, but something that allows for some sort of trial period would be acceptable.
Thanks!