This is a pretty clever idea for a Kickstarter project. It's called Fraemes and basically it's all about 3D printing thin back overs which snap into a case like orientation. You can quickly change the look of your iPhone case by simply swapping out the back cover. They will have a shop so you can buy different frames and the designers of each will get a cut of the proceeds. They are seeking $15,000 from Kickstarter backers for this project, and will be working for cases for the new Samsung Galaxy S5 next.