Looks great! A lot of work!
I've made some cans too, not many channel letters yet, but a few.
You may want to pick up an expander/shrinker from harbor freight sometime. I've been using the shrinker on the sheet metal U channel to make round corners or gentle radiuses. You have to shrink one side of the U leg, then the other, and after a while get decent at it. Then you dont have to make the triangle cuts to make corners. Although if its hidden, why not?
If you look in here there should be a few examples like on the ford sign.
https://www.facebook.com/search/posts/?q=road%20rash%20restorations%20-%20r3This video may be handy
https://www.youtube.com/watch?v=YjGBZhGwxwg