As part of my training certification for the Edgerton Center Machine Shop at MIT, I machined a personal flashlight from two solid pieces of extruded aluminum.
The top piece of the flashlight was machined from a solid rectangular prism of aluminum using a standard mill. End mill tools were used to face the aluminum block and create the lens cover recess. Drill bits of varying sizes were used to create the light bulb recess, the screw holes (hole threading was done manually), and the conduction shaft to allow the light bulb to make electrical contact with the battery. The bottom piece of the flashlight was turned from a solid tube of aluminum using a standard shop lathe. The part was faced and cut at a 30 degree angle between shaft and holster, a battery recess was drilled, and threading to connect to the upper part was done manually.