This tutorial will go through the basics of creating an Iphone Case, but will use the Iphone 7 as an example. To complete this tutorial it is trivial that you understand basic parametric CAD features. The features that will be used are sweeps, extrudes, extruded cuts, and fillets. These instructions can easily be adapted to any Iphone. I personally use Solidworks, but Onshape, Fusion 360, Inventor, or any other parametric CAD program should work great.