There are so many survival tools that you can find on an iPhone, such as a compass, a map, a flashlight, and first aid instructions. But none of these things will let you cut an object. That’s why Instructables member Mike Warren’s invention is so handy. His iStab is an iPhone case that has a built-in folding knife blade. He made this piece of cutting edge technology with a 3D printer and a cheap paring knife.
First, Warren found pre-existing designs for folding knifes and iPhone cases on Thingiverse. He mixed them together in Meshmixer, a 3D design editor. He then used an Objet500 Connex to print the case.