Transperancy

I am working on some projects using transparencies. I would like to use an overhead projector to display it to you but it graphs layered on top of each other as if they were double exposed. The two photographs layered are contrasting images of the past and the present. I would like to also use transparencies along with drawings that reveal the type of emotion that is contrasted with the omission of the photograph but I'm not sure exactly how I should do that.  The idea behind the overhead projector would be to show an image on the wall as art but also as something intangible.  The art itself is only a light. I'd like to possibly play on the scale with these images.The overhead image will be large and the printed images will be small. I've also thought about lighting the images from behind using a lightbox. My concern with the overhead checked it would be that they will be more visible then the images shined on the wall. I don't necessarily intend for it to be interactive, although if it works well I'm open to it.