[Tetraman]

Google Sketchup is not CAD, nor is it useful for CAD applications. It is a program to make 3d sketches, not 3d final products.

There are, to my knowledge, no libraries of any FIRST Robotics parts - however you can find most of the recent year's Robotics Fields.

There are ways of opening AutoCAD files into Sketchup, however you will need the Pro version of Sketchup to do this. If you can afford Pro, just simply do a Google search for uploading CAD files and you'll get your how-to's. I just did, took me 10 seconds.

I use Sketchup quite a bit, but since I use it for art and basic design purposes, that's all I need anyway. When designing a robot chassis, or any part of the robot for that matter, I would rather use what BJC suggested of either Inventor or SolidWorks. The extra options both of the programs have make actual building of things much easier. Inventor is better for FIRST applications, but SolidWorks has its charms.

Sketchup is a very useful and, in a way, powerful tool to use - but it doesn't have a chance to become a staple of FIRST design tools when you already have access to Inventor and SolidWorks. Go with what works.