[MrForbes]

Our team bought a lot of structural material before our first build season, and ended up not using most of it.

If you are going to get the kit chassis, then you will already have your main frame. Once you decide how your team will play the game, then you can decide what your robot needs to do. Once you know what it needs to do, you can figure out how to build it.

We have been quite successful using rather mundane materials, purchased locally, as needed, such as plywood, aluminum angle and round/square tube extrusions, and sheet metal and polycarbonate. Rivets and sheet metal screws and small machine screws and nuts can be used to hold these parts together. Look at lots of pictures of robots from past competitions, you will find there are many ways to build. Some of them require hard to find materials, long lead times, and lots of expensive machining equipment. Others are quick, simple, cheap, and clever instead.