I've radically changed the assembly process for the Dagu camera robot chassis, I use the USB power pack but found that mounting it between the wheels on the 'lower deck' caused stability problems, the slightest unevenness while the robot was moving would cause the power unit to foul the wheels and disrupt control (sending the robot in ever decreasing circles !). My solution has been to move the Arduino to the 'lower deck' and attach the power unit to the 'upper deck' with a couple of strategically placed strips of velcro. I need the support posts between upper and lower decks to be extended by about 0.5 inches (in old money), this could either be by longer replacement posts or 'screw in' extensions or 'elbow' connectors for the Arduino header pins so that connecting wires can be attached parallel to the PCB.
I've had no luck sourcing them locally (Maplin's etc) - can Dawn Robotics supply suitable replacements or suggest where they can be sourced.
John Doobson