One of the great things about 3D Printing is that complexity is free, which means customization is free. We have a large number of co-creator designs in the Shapeways galleries that are customizable, which means if you are a designer, you can offer to modify your designs to your customers requirements. If you cannot 3D model it means you have a way of getting a designer to customize an existing designs to your specifications.
Here are just a few customizable iPhone accessories from the Shapeways gallery.
This is new. Up until now I have seen only the cases and covers which were customizable only based on color and images. 3D art is something new and unique. Are they customizable as well? ... If yes then do tell me from where I can find the cases and covers