A 15" block well padded to serve as a hot pad/table decoration is a perfect idea.
You could even stuff it with potpouri. When something hot sits on it, it activates the fragrance.
Back when my mom first taught me to sew, I was practicing blocks. They were very poor quality. But, I made them into pot holders so as not to waste anything. The first one I made is sitting on the counter in plain view. I cringe when I see it.
She keeps it like she kept my kindergarten finger painting or poem projects.
(It does look like a kindergartener made it too.)