mechanical /mĭ-kăn′ĭ-kəl/ adjective

Of or relating to machines or tools.
"mechanical skill."
Operated or produced by a mechanism or machine.
"a mechanical toy dog."
Of, relating to, or governed by mechanics.

You’re using the second definition and everybody else, including me, is thinking of the first or third. I would call anything that has a mechanism integrated into it, such as a manual slide that covers a camera, to be mechanical.