No need to take measurements to build a model for a 3D-printer or CNC machine. This cover was made by hand with Instamorph, a plastic that turns soft when heated and strong when cooled down to room temperature.
There are plenty of cool cell-phone cases out there on the market, but they are all produced by someone else. Tome to take things into you own hands and make one yourself.
Step 1: Making a Dummy
You could try to build the case around you phone. It would fit perfectly and, depending on how you shape it, never fall off accidentally. I wanted a case that I could take on and off. And I didn't want to risk damaging my phone. I had never worked with Instamorph before.
My Idea was to make a copy of my phone and use it as a dummy to work on.
I already have a silicone case that I used as a mold to cast concrete in it. The concrete I used is meant to be used to build kitchen tops. To give it more strength it is mixed with fibers. So even though the block of concrete is just as thin as a phone, it is stable enough not to crack or break.
You could also try resins. Make sure to use some release agent then, otherwise your dummy might just get stuck in the mold. ;) The concrete came out perfectly without any release spray.
I just used some scotch-tape to seal the open holes and poured the concrete right in.
Tap it for a while so that the enclosed air-bubbles that are trapped in the concrete can float to the top and pop. Otherwise you will have tiny holes in your dummy.
Step 2: Prepare the Instamorph
You'll be surprised how little material you will need to make a case like the one I made. A few spoons will be plenty.
I start with one spoon at a time. Put the pellets in a bowl and pour hot, boiling water over them. Very soon you will see that they will become translucent. That indicates that the material is warm enough to be molded. the little pellets have become sticky. It's easy to get them all out with a fork.
When it cools down it will turn opaque white again and retain the shape it's in.
I then made a roll. Go back to your childhood days when you were using playdough. ;)
To get an even and round roll squeeze the Instamorph roughly into a long strand an then roll it with your flat hand or a piece of wood over the table.
The next step is to half the roll and stretch it out to it's original length. Effectively doubling the length while reducing the width by half.
Do that a few times. I managed to get 16 thin bands out of one thick original one. (See comments in the picture above)
Make a few more at various thicknesses and keep them at hand. Make sure to have a few thicker ones to be the base all around your phone.
Step 3: Reheat and Apply
Now it's time to build the actual case. Take one or two of your thicker Instamorph sticks and reheat them in hot water. (You'll probably have to reheat the water again.) Then start to wrap a bumper all around the phone. This will be the base to wich all strands that go over the back will attach to. Make sure to go just a little around the corners so that it will have enough grip. But not too far over the top side as you will want to take it off later on. Use an existing case for reference if you have one.
Then cover the back face. Style it totally up to you now. Mix thick and thin, straight or curvy lines, whatever you like.
Chances are, that it will take longer to apply all the sticks than the material will stay clear and moldable.
You can dip the complete dummy in hot water to re-soften everything or use a hair-dryer or heatgun to do the same.
Go all around your phone and check if all the loose ends are connected and that there is enough material around the places where there will be openings later on. (headphone, power, mic, speakers, volume buttons...)
Step 4: Taking It Off
Once it has cooled down again (which you can accelerate with cold water), slowly and patiently peel it off the dummy. It won't come off easy and bits and pieces of the concrete might break off and a few will be stuck on the inside. But Instamorph is very flexible yet won't stretch too much when pulling it off.
This is the hardest part and takes some courage. Trust me though it does come off. ;)
When it's off it time to clean it out. There will be some concrete stuck in the cornerns and where the holes were covered with tape. I got most of it out with my hands and a sponge.
Then take a knife to cut out the holes. I used a Dremel to drill small holes in the corners as a guide and cut out the part in the middle with a knife. Be careful, those knives are sharp!
Step 5: Putting It On
Now it's time to fit it onto your phone for the first time.
Again take your time. If it feel too hard, too tight, feel free to cut away a little on the top side until you can squeeze it over.
Look around did you cut open all the right places? Do all the plugs fit? Looks like you're done. :)
Enjoy the fruit of your labour, there's still time to even out all the little details you missed.
Step 6: Build the Next One...
Your Dummy should still be in good shape to build another one. The first one I've build didn't meet my expectations at all. The second one turned out way better. So don't give up if it didn't work the first time.
Remember you can take the old one, reheat and use it to start all over...
Instructables provided the Instamorph for this project as part of their "Build Night" program. Make sure to chek that out and see if you and your local maker-space cares to participate in one of the upcoming ones.