do you even have experience with normal RC tank making?
http://www.youtube.com/watch?v=Oo3zWxO3yYsdo something like these
Antweights are cigarettes.
Whatever you make, add a stereo that plays this: http://www.youtube.com/watch?v=waYbqBb4yNA&feature=related
A lot. But it's a lot more fun to fight with them.
Building the robot would take some machine skills and you'd have to program it too. I recommend Robot C.