MIT 2.670 Mechanical Engineering Tools course: Over the course of three lab sessions, I manufactured a fully-functional flashlight from stock parts using machine shop tools including the bandsaw, CNC mill, lathe, drill press, and tap and die set.
The flashlight is made up of two parts: the head and the handle. The head includes a light bulb with a protective acrylic lens. The handle includes grooves for grip and a hollow opening which holds one AAA battery. When the head and the handle are screwed together, the lightbulb, battery, and aluminum casing complete a circuit which turns the flashlight on.