We made significant progress on every prototype, performing at least on test on every design we were working on (there will be many more to come). We tested a claw to grab the totes, and found that it can deform the recycling bins in such a way as to make them easier to grip. After adding wheels, the claw was able to bring objects into its grasp (when the wheels weren't falling off, c-clams are a makeshift way to hold motors).
We also tested an elevator with built in hooks to lift up totes by the lip, which functioned to some degree. In that line, we also tried a snake of hooks that bends back upon hitting the side of the totes to more effectively grasp under the lip (it's made from interconnected door hinges!)
Finally, we tried an extended pneumatic arm to grab the recycling containers in the middle without having to move the totes out of the way first. We even took a video of a test:
In our quest to stack many totes, all I can say is: