Don't bother with "patina" metal". Have a sheet metal shop bend a new piece to the dimensions you need, paint it with white vinegar, and toss it out into the weather for a few weeks. "Instant Patina" and it won't give you as many headaches when welding it into place.
Jerry
Nice tip Jerry. I tried H2O2 but it didn’t make much rust. Might try your idea.
