My LED strip running underneath this gap and would shine in my face from certain angles, this plate should press-fit to block the ugly gap, incompatible if you have a front-mounted radiator (hopefully that would be fairly obvious).

I have 3x corsair LL120 fans at the front and the small rubber feet on the back stick out so I had to make some indents on the underside, feel free to edit to fit your needs better.

Printed with 25%+ infill to block light from underneath.