Our team is entering our second year in the 2016 season and we're trying to do plenty of training and offseason work to be very competitive in our competitions. Last year we went to Worlds and I had the chance to look out some robots and there was a variety of robots that used a sheet metal chassis and some that used a 2x1 aluminum tube style frame.
Thus begs the question: tube or sheet frame? We recently got a sheet metal/fab sponsor so tooling won't be an issue. We also are planning on getting a decently sized CNC router so making standard gussets and custom sheet parts won't be an issue, but we definitely don't plan on making a chassis on it. My current 2x1 aluminum tube based project (Hex shape just for kicks):
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