Hey, I did kind of the same thing for a prop space ship motor i built for a TV show. In mine I used a Mac SE/30 to display B&W boxes behind a multi colored sheet of gels. To diffuse the colors even more I used a large Fesnel lens in front of it. Lookes pretty neat if I say so myself. I’ll have to post photos of it.
“The Groovetube is simply a translucent plastic box that suction cups to the screen of your television. It has a grid of dividers inside it that diffuse the colours from your T.V. producing an amazing colourful abstraction of anything you watch…