I recently bought the Samsung Galaxy Note II and noticed that there were not many cases available. So I decided to make my own. After doing this I thought it was a good design exercise and thought I would share it.
Step 1: Design Phase
This is the most important part. To start with you will probably need a set of calipers so you can measure your phone. Input the length and width of your phone into Autodesk Inventor then extrude to the thickness so you get a block about the same size as your phone. Since we are going to make a case we want our block to be bigger than our phone by about the thickness of the case. So if we are making a case that is 0.100 inches thick then we need to add 0.200 inches to the length and width, and 0.100 to the thickness.
Step 2: Adding Shape
Phones are not square. They have many curves and contours that need to be accounted for in our case. Measure the curves and angles of your phone and input them as fillets and chamfers.
Step 3: Is It a Case?
So we now have an oversized phone simulate but it's not a case. The shell command will take care of that. Make your shell the same thickness as the extra you added in step one. 0.100 inches for example.
You may see that my thickness is 0.050, I found that with the Makerbot this is too thin to use due to strength issues. I recommend 0.100 or 0.150 if you are going to print it on a Makerbot.
Step 4: Feature Rich
Your phone probably has a camera, flash, earphone jack, charging port, power button, volume rocker, and at least one microphone. Currently our case is just a cover for the phone and won't allow us access to any of these features. This next step is to measure these features and their locations then cut out places for them.
You are going to create a new sketch for each face that has features to add (or you could create a new sketch for each feature) and then do an extrude cut to make an opening for the feature.
Step 5: Let's Print
Once we have all our features in place we can export an .STL file for use with Replicator G or Makerware. Import the .STL file, create your gcode, save an .S3G file, and print your case.
You may find that your case isn't quite right the first time out after all some of the measurements can be hard to make. Also depending on the material that you use you may get different results. So after you print you may need to go back in and tweak your design a little.