• 箱入りはこいり — boxed (item)
• 重箱じゅうばこ — multi-tiered (food) box
• 手箱てばこ — small container
• 箱船はこぶね — box-shaped boat

箱 is composed of the radical 竹 (bamboo) and the phonetic component 相 (shou/sou). It originally referred to bamboo-made containers. Today, it's used for all kinds of boxes, including lunch boxes, storage, and packaging.