Many years ago I started collecting glass tea lights. They are large enough to hold a regular size teapot and keep the pot warm with a small votive candle. I really do not remember how many I have in my collection, but I know it is more than 15. Most are at least 20 years old, since I have been collecting that long. Two years ago I found an unusual one in England at a charity shop.
Oh, charity shops! Things that keep the Antiques Roadshow alive!