(Note: Include a pic of your problem and your question gets posted first.)
What would I use to put on top of a radiator to use as a type of table or decorative piece?
Dear Natasha, our top pick is marble, which is both heavy (and therefore stable), resistant to the heat and a great natural texture.
We found old pieces of marble in our yard on Bedford street that had been used for plantings. You can find precut door saddles which may fit your radiator OR get a custom piece made at most marble and tile shops. We called Nemo at 48 East 21st Street (212.505.0009) and they will do both. MGR