Here is a simple Bot Shots Arena I tossed together to play around with at conventions. Its fairly straight forward: Black Poster Board, blue and white tiles are Lego, art from the packages.
I used two Megatron Launchers because I found that the Prime one doesn't work quite right. Just slapped some Autobot decals on the one so that we still had an Autobot vs Decepticon feel to it.
Most importantly it works really well.
Here is a more overhead shot:
