You could make your own using a Dremel tool and a piece of acrylic. It would match the look of the case, though I think you want metal. You could find an existing grill that looks similar and take the Dremel to that one. Or buy a fan grill blank.

I did a little research and found that there is a company that has premade grills, but they also offer laser cutting services. You may find something over @ Lunagen Labs. They have the tools, but like a book, don't let it's cover fool you.
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