Not all of the electronic components came out of the box for the robot, the relay for the motors needed some adjustment(the motor controllers could not spin the motors backwards, these SPDT relays switched the polarity), they could not handle the amps that would pass through them. They originally looked like these...

I had to remove the blue relays and replace them with these ones. 

All the electronics are placed on the under side of the plywood on top of the robot. The wires leading up to the motors have connectors on them so if I later choose I can remove ten screws and the entire frame becomes free from the electronics board. This way I can use the same electronics board for different drive bases.

Relay Top

Relay Side

Motor speed controller

Here is an early stage of the wiring, Arduino Mega mounted, and powered, the two relay's mounted, a motor controller mounted, and power distribution boards mounted. 

The robot communicates with the control board via the X-bee wireless communication chips, both on the Arduino Mega, and the Uno on the board.