One of the delights of life is to happen upon the casual application of imagination to the banal. (That's why I get annoyed by the pretentious posturing of starchitect poseurs who work so hard to gild the lily.) Talking about banal, old French MANHOLE COVERS would seem to fit. (In Seattle we call them personnel covers, if you can believe it.) Take a look at how a bit of effort can inform even the most mundane things.
Thank you Michael Jennings for the link.