To clarify, the two pieces to be joint are not sheet metal.
See images.
Attachments
38807C05-9463-45BA-81AA-AECDD04BA89B.jpeg (279.76 KB, 145 downloads)
4DD70645-2DEC-4884-916F-49F88A0D5F20.jpeg (323.24 KB, 142 downloads)