On the exterior section I ripped the outer leg of the 1/2" aluminum angle to 1/4" so it would not be seen when the door is in place. So annealing of the aluminum is not necessary, it will easily follow the door opening contour.

I used the same jig to set & countersink the screw holes. Use stainless screws here too. Same two pieces, the hinge side & the longer section. The longer section goes in first, then measure cut & fit the hinge section. Once you have a good fit, remove caulk & reinstall. This picture shows the trim in place, but not yet caulked.
Installing the Exterior 1/2" Trim