[MichaelBick]

We also like aluminum tube. Really, the best thing to use is 1 x 2 aluminum tube, welded. 1/8 in thick for drive base, and basically 1/16 for everything else. If used correctly it is perfect. Minimize the amount of frame material you need. Look at any 254 robot, and you will see how simple the frame actually is. It makes for lighter robots, and you really don't need anything more. Also, 1/4 in, waterjetted, aluminum plate goes very nicely with this. It makes building 20 times easier, and reduces the amount of tubing you need. Plus, you can make custom gearboxes. Really, it pays off to get a 2D sponsor, as they can turnaround parts amazingly quickly.

On the subject of sheetmetal, while a lot of good teams use it, there are plenty of good robots built out of tube, as long as you streamline the design process(254 again comes to mind). The nice thing is that the robot comes together lighter, more quickly, and more accurately than an aluminum tube robot. On the other hand, you need to have a good team of CADders, and have the sponsor to be able to do it.