1. Is the Sphere stable within the box, aka when you open the lid does it just stay there?
2. If yes, take one level of Rogue, and then one level of Barbarian.
3. Rage + Expertise in Athletics = grappled targets and stuff them into the box.
4. If you have a class with access to Polymorph, have them Polymorph you into a Giant Ape for the bigger enemies. Then stuff them into the box.