thanks for the comments
Our robot carries tetras pretty stably, but the drive train seems a bit squirrely. You can't really tell from the vid, bc it's only supposed to showcase our strong points
It's 2 drive wheels powered by 2 CIM motors each. There are 4 castors in each corner of the chassis. Sometimes, the robot gets stuck on a goal bc of the castors! We put guards on the castors, and now it's a lot better, but it still (rarely) happens.
We were supposed to stack more than 1 at a time, but it would be less stable when stacking, so we just went with 1.