After reading this and seeing how much time you have into it, you have reinforced my love of aged aluminum patina. Nice job, but I don't have the patience, i would have gotten 1/4 through the top, and stopped.
It is a complete pain in the *** but I try to keep my eye on the prize. I biggest problem I am having now is finding the perfect amount of beer to consume whilst sanding! Too little beer and the job is almost unbearable. Too much beer and I forget I'm sanding and I'm dancing in the garage like nobody is watching.