Well, my stuff isn't quite 4:3 but they're all the same size. Unfortunately my Polaroid printer doesn't stretch but always remains the same- and the print is small enough that I want to use the full image area. As it happens, I've seen a fair number of images on the web that depart from this ratio. Still, merely changing your canvas dimensions doesn't seem much of a challenge. I would think that would require more arresting imagery. I guess I'm saying that I don't care about the size of the box. It's what's inside that counts...