T-shirt bot mechanical design requirements

[cxcad]

Thanks everyone for all the input,
asid We are kind of low on budget right now, so we are seeing what we can do by ourselves, though probably for the season we will buy something COTS. 8 lb chassis is just the metal framing. Thanks for the recommendation on hex shafts.

DampRobot For the regular season, we are probably going to use a lot more COTS components. I feel that by going custom, the students will be more involved in the design process; we also want to try out some possible sponsors. I do not see how a custom gearbox will be any less efficient than a COTS gearbox; we have a fabrication sponsor that can nail a four ten-thousandth of an inch in tolerance.
I hate the fact that we are pretty much copying the poofs machine. During the summer we did some research, and thought that going with a tried and true method would be better. Any suggestions to differentiate the robots.
Runaway Better than the poofs . I will put some thought into those constraints. I'm trying to limit chain, because I do not want to dealing with chain tensioning.
aside Good idea. Will make those changes soon.

Anyone have any suggestions for teaching how to make this robot? Also what do you guys think about skipping the single barrel design and going straight to 254 style gun?