Answer:
The fuse box is constructed of a rigid plastic. Each individual fuse fits into its own slot. On the bottom side of the fuse slot there are provisions to hold a brass, aluminum, or gold pin. These pins get crimped or soldered onto the end of a wire, are inserted into the fuse panel, and are held in place by various types of "strain relief" usually clamping onto the wire insulation somewhere so no force is placed on the copper wire itself. The fuse fits into this pin tightly to make connection and supply voltage to a circuit. The main power wire to the fuse panel is usually a larger wire - 4-10 gauge and has an eyelet on the end. The eyelet fits over a threaded stud on the side of the fuse panel and supplies voltage to one pin of each fuse or relay.