As for 3D printing,
There seems to be no restriction as to how much we can 3D print (I myself have printed out about 13 gears, modified c-channels, and barrier sleds). Surprisingly not many parts are 3d printed, and most of what I print can easily be made from cutting/drilling regular parts/polycarb (so far…)
If ANY part, even a little nut or zip-tie falls off/detaches from your bot during a skills match and the ref sees it, you are disqualified from that match (we only have 3 attempts each for auton and driver), so there is a strong incentive not to have something shatter (that would also lead to saftey penalizations, which is another big part of the rubric).
If you saw that post I made on the “share pics of your bots thread” of my drivetrain, all the bright red gears are 3d printed.
I’ll have to ask my sister team (I haven’t attended a comp yet, this is my first year competing).