Designing a new product is one thing, but making it capable of rolling out of the machine in the factory is a whole new thing. It's the difference between papers with a staple in it or a nicely bonded book. It's in the details like Moldflow simulations, stress strain calculations, FEM analyses, material selection, tolerances, surface finish etc.
At my internship at We Are Perspective one of my project was to help with a teleconference device. Making 3d models, technical drawings, calculating tolerances and computing product strengths.