I needed a white metal supply air outlet for my HVAC system. Commercial items are usually rather expensive, nevertheless I did not find something I really liked for my environment. Then I stumbled upon a couple of Algot shelves at the as-is corner for €1 each, they were just perfect!
So I made a custom wood plenum (casement) for each one and installed them over my drywall ceiling. Four neodymium magnets keep them steadily in place from inside. You can hardly notice them, they’re easy to pull off for cleaning and, most important, they’re hacked! 😉