[OccamzRazor]

I am surprised there has not been more support on this thread for using 80/20 or Bosch Profile T-Slot framing components. Yes, we love and use rivets, but the question was more about which option to use if you are bolting gussets to extrusion. I would say neither if you can afford to go the route of T-slot extrusion which will allow you to bolt a gusset on either side of the extrusion with fewer protruding bolt heads.

The T-Slot fasteners take a LOT of tooling time away from the construction of the robot parts and you get the plus side of loosening the fasteners and adjusting the position of the components without drilling any holes most of the time. We use this for prototyping every year before we transform to a lighter design. (probably with rivets)

Check out an 80/20 catalog to see what they have, they even offer a lightweight version for robot construction and some suppliers offer discounts to FRC teams through the company. We even got about $1000 in parts and extrusion donated this last year for our pit.