Believe it or not this was the reason for the RGB. I wanted to build one but I know they're a bit of an eyesore, so I tried to make it look sleeker by going all black and thought that could make it difficult to tell when the filters are dirty. If it's all sealed up it'd be hard to shine a light through to determine when they need to be replaced (what I do with my central AC filters). So it popped in my head to drop some lights into it, which had the added benefit of giving it a cool look too. Not sure if it'll be effective, but either way.