[asid61]

We have traditionally used 8020 (for more than a decade) but I'm starting to shy away from it myself. The skill level of those who are putting it together coupled with the poor dimensional nature of the stuff makes me want to move towards 2x1 and 1x1 aluminum tubing next year. Predrilled or fabricated, I don't care.
I ran the mill this year, and for the first two weeks of prototyping I just sat idle and cadded away. Drilling hole patterns in 2x1 takes almost no time at all once the mill is set up. It's much, much more precise and makes people actually design in CAD before building, not to mention it's faster/easier (at least for us).

Last year was one of our worst, largely in part due to a massive 4 weeks of prototyping before deciding on a catapult. The prototypes were terrible indicators of whether or not an idea would work, as they did not resemble the final design and were sloppy in general. Forcing precision is my goal next year.