Are you looking for how people did it in Inventor or how teams did it on their robot? You could peruse the picture arcives and teh robot showcase section for pics.
As far as how they did it in Inventor, it dependes on the setup. It looks like petek used prefab Alumium angle with holes in it on the robot, so made an extrustion to the right length and patterened a hole on the sides to make it heve the holes. (this is how I would do it, atleast). Our bot's arm was made out of sheet metal (
Here) and I used the sheetmetal tools that Inventor provides. Each section came in 2 parts (so they could be bent and assembled correctly).
If it is a prefab part (like those crazy extruded alumium pieces that are so nifty and my team won't use) you might be able to find it at
First CAD Library . It hasn't been updated for a while, so check CD to see if the new site I got people started with will pan out.