A welding apparatus for making an automotive light including light guides having an inlet which receives the fibers the laser beam produced by the laser emitting device and an outlet which propagates/transmits the laser beam collimated by said guides. The light guide has respective free ends mechanically separated from each other, wherein the light guides are configured so as to direct collimated light beams on adjacent and locally continuous portions of welding interface so as to obtain a homogeneous and uniform distribution of the light beams along the welding interface.