There are reusable shipping boxes made from similar materials. Those don't work as well with a robot, however. I do still plan to get a lifting arm/manually-op

There are reusable shipping boxes made from similar materials. Those don't work as well with a robot, however. I do still plan to get a lifting arm/manually-operated crane. It would be nice to not have to lift them with my spine, and these are made for reliably grabbing by a robot. Both from the sides and even from the top (when tightly packed). (There are 4 access holes on the top that go down next to the grips on the short sides. A grabber uses one hook each to lock the box when unloading e.g. a pallet.) You should be able to order from a company like Auer Packaging or a local alternative. Thankfully these are specified precisely, so manufacturers can't cheat on stability to save materials. They actually recycle well, btw. When broken/used-up, they'll get shredded and turned back into new boxes. It works because they're pure PP and only one of a few fixed colors.