The std under mounted Arduino Mega 2560 (Rev3) with component silkscreen and text added to PCB view.
The USB, and maybe the power connector, will hit any PCB component pin that is mounted directly above it, so I added the Arduino Mega 2560 component positions so you know were to place them. Even if you file the protruding pins flat they will still hit the USB, so it’s either avoid those positions or space the headers higher to give the Mega more gap to the PCB.
UPDATE 10 Dec 16
V1.1 - Arduino Mega 2560 (Rev3).fzpz (89.4 KB)
As per my other ones, the holes don’t get drilled. You have to manually put holes on the circles were you want them, this is to allow a choice if you are running out of room and have to run track through a hole.
REASON FOR UPDATE
For some reason when I put my new silkscreen Mega on the old std Mega from the Arduino bin, it wouldn’t snap exactly on the old part. With a 0.025" grid it would snap 0.015" left or 0.010" right.
Also when you zoomed in half the USB and PS plug would disappear.