MIG like TIG welding: Just Say No! 

This video does a deep dive into the shallow end of welding with MIG such that it looks like TIG. MIG- or Motorized Inert Gas- welding uses a drive wheel to push solid core wire through an electrified tip, arcing and liquifying the wire as it gets pushed into a weld. TIG- or Tungsten Inert Gas- welding uses a electrified tungsten rod to superheat a small area between the rod and the metal to be welded. Filler metal is added manually by hand to the molten pool of metal. MIG makes an even weld looks, whereas TIG makes a circular patterned look. Some fabricators use MIG welders in a bizarre technique such that it appears patterned like a TIG welder would make. Unfortunately, using MIG in this fashion greatly reduces the structural quality of the weld. I would be highly discourage the method unless you are certain that the alternatively welded object meets the structural requirements of the part's use. It does look fabulous if you like the way TIG looks, though!