Does such an item exist?

I'm imagining a holder that will fit in a typical 4x5" spring back and that holds the film (or plate) behind a glass pressure plate.

The reason I want one is to make some experiments with screen-plate color photography. My screens are made by taking a picture of a TV screen onto 4x5" slide film... I call it, the TV-screen-plate.

My biggest challenge so far has been getting flush contact between the screen & the film behind it. I saw something that resembled this on APUG once, and if I can find a link I'll post it.

Thanks in advance