Fun inexpensive camera accessories?

Hi ya'll

I have been asked to think of a sub £20 gift and I was thinking some camera accessory. I like film photography and I use Nikon (for their interchangeability).

So I'm looking for something for an F, F2, F3 or F4. If film camera accessories are not an option, something for a D200 or D300 would also work.

I'd like to note that I'm not even sure if it's possible to come up with anything for this price but thought I may as well ask. I was thinking something like a remote release or focusing screen etc.

Thanks for any suggestions:)

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