You know how people collect buttons? I don't imagine it's all people, just the ones that sew. Buttons often of unknown origin, gathered together in a box. Sometimes, a tin box that once housed biscuits of some kind.
The specific button box that inspired this manicure wasn't a former biscuit tin, actually, it was a collection housed in a tupperware. Points for originality, I guess.
To be honest these were too many colours to remember, but I do remember it was done in all polish, because I did it when I went to England and had no paints. And yet I had all these colours, hah (except for the light purple from the heart shaped button, that one was borrowed).