metaphor for short-term or working memory??

Can you please help me find a metaphor for short-term or working memory and provide examples?  I just need a little jumpstart on my paper.  thank you.  I really appreciate your help. i really hope that your help is MORE than just a sentence/suggestion or two.  I am a poor college student.

Many metaphors have been used to describe cognitive mechanisms related to short-term or working memory. For example, STM has been likened to a computer (or part of the computer, such as RAM), or a workbench, which has limited space. Create a new metaphor for short-term (or working) memory. Do not use any metaphors you have ever heard of before (i.e., do not use a computer or a workbench). Describe and explain your metaphor/model. What aspects of short-term memory does it capture (e.g., limited capacity, brief duration, rehearsal)? You may tie your idea in to sensory store and/or long-term store, if you like, but that is not necessary. Feel free to use diagrams, but be sure to verbally describe everything.

1. Keep focused. Remember to answer the question and only the question

2. Be concise. Remember to say alot with few words. (Paper is only one page, double space.) The paper can be longer than one page, only if it is absolutely necessary.

3. Include all important points.

4. Start by brainstorming (check your notes and the book). Develop an outline.

5. Be clear. Each paragraph should express its own idea. Include introductory sentence and concluding sentence for paper. Good flow is a must!

6. Be grammatical.