How about a frame where the surround was morphable for thickness etc., as well as the picture area being adjustable for aspect ratio? I understand what you mean about the mapping. If I assign a separate material zone to the picture area, you can then apply any borderless image file directly to it in the material room. That should be quite simple to do, but I have limited time to play. If you aren't in a hurry I'll try to put something together in the next few days.