I read about other people using tracing paper and spray adhesive to trace the plans and attach them to the metal. For some of the parts without dimensions labeled in the plans this seems to be the most convenient method, so I decided to give it a try.
Here the tracing paper has been glued to the aluminum. I think a somewhat weaker adhesive may have been better–once the paper touches it is difficult to move.
I was able to remove the tracing paper, flip it around and reuse it to make the mirrored parts. Yesterday I started using some of the sanding attachments on my dremel tool to finish the edges–especially the inner radii. This has worked well but it seems I’ll probably go through a sanding attachment just about every evening. I have a bunch that I was probably never going to use, but I might look into getting something better like small scotch brite attachments.