The image of a tin can, that has once held something, but now is depleted or vacant, is used to depict a sense of emptiness or insufficiency. It emphasizes a state of being devoid of substance, value, or significance. When used metaphorically, it suggests that something is hollow, barren, or devoid of meaningful content or characteristics.
Here's an example to illustrate its use:
"Mary's eyes were empty as an old tin can after the breakup. All the life and spark seemed to have vanished, leaving only a vacant expression behind."
In this context, the metaphor captures the emotional emptiness that Mary feels after experiencing a breakup. Her eyes, usually a window to her emotions, are described as empty, like the void left by a used-up tin can. The image conveys the sense of desolation, loss, and lack of vitality she experiences in that moment.