The chassis is purchase-able on the internet, sorry but I have no time to search for it now, but you can find it on many big robotshop sites.
I especially like the PCB on top, looks nice.
Expandable, large enough, test print in empty areas, etc... Great for hobbyists.
constructive comment:
Make the bot turn when it sees an obstacle without stopping.
That will make the robot look much more fast and natural.
