The iPhone 4s template I used to get all the dimensions can be found in the the following link:
I also attached a picture of all the measurements of the case itself.
Step 2: Renderings
Here are some of the iPhone case Renderings.
Step 3: Print Out Case Using 3D Printer
After you finish drawing the file, save it as .stl file and send it to the printer.
Step 4: Final Product
This is the case rendering compared to the actual case.