<p>It looks like the back of a 4x5 large format camera to me, like the part that holds the ground glass and is flipped out of the way for the film cassette. The axis of the piece in the first photo looks as though it would open so that the film is loaded (or scene viewed) in a portrait orientation by default, which is atypical, and may help refine your search. I think you're right that this is a camera piece given the proportions of the opening.</p>
<p>FWIW, the piece in the center does not look like anything I've ever seen on a camera. At first glance it looks like the wind plate of a TLR but then it has those decorative raised bumps along the perimeter, which is unlike any decoration I've seen on a camera or camera equipment. <br /></p>
<p>It's a relief to know that even in a galaxy far, far away they never standardized on Phillips-head. Flat-head, Phillips-head... it don't matter.</p>