This sounds like an interesting project. I'm thinking try to leave a
bit extra so that you can bend the edge over with clamps and straight
edge, then carefully flatten- if you hammer, you'll have dents all
over- need to squeeze it. It is not likely to turn out cosmetically
perfect- ideas such as this seldom do, unless you're pretty skilled
You don't say how you intend to use it/ whether perfection matters.
Sometime toward the end of this piece of work, $100 might start to seem
pretty reasonable. I speak from experience.