At Macworld/iWorld 2013, I ran into Tavis Schriefer, the president of a Texas design company called Ideative. Schriefer only had a few minutes to chat, but he demoed a customizable iPhone case that was stunningly simple in design and execution. The frām case (US $34.95) makes personalizing your iPhone case with just about any photo or artwork a quick 90-second process.
The frām case, which is currently only available for iPhone 4/4S, uses a clear polycarbonate back to protect an image or photo that is cut to the shape of that back. In fact, the back is easily popped out of the case and becomes a template to mark a photo for trimming and placing into the case.
You can literally use any photo; it doesn't matter if it's something you printed out, an old family photo or something in a magazine. Just place the template / back onto the image, move it around until you like what you see, and then use a pencil or pen to mark your cut lines. Use a pair of scissors or a knife to cut out the image, pop it into the clear frame and push your iPhone back into the case. Voilà! You have a personalized case. You don't even need to cut along the lines very cleanly -- the case design uses a slight bezel to cover any imperfections.