I have an item:  Honey

This item has several varieties: Almond, Blueberry, Orange Blossom, etc

This item has several sizes: 6oz, 1lb, 6lb, 12lb, 60lb

The customer goes to the item page (Honey), then chooses a variety and size.

A 6oz jar is the size of my fist.  A 60lb bucket is a 5-gallon bucket.

Each size has it's own shipping box that it can go into.  Obviously a 5-gallon bucket is much larger than a 6oz jar (the size of my fist).

How can I assign a different box size to each honey size?  Most importantly, I need to ship the 5-gallon buckets by themselves.  At the moment, other than assigning the largest box to all honey sizes (which would grossly inflate the cost of shipping a single 6oz jar), I don't see how to do this.