Oliver has a lot of fun projects on this site – “Homebrew hardware, including a homemade TIG welder, focus fusion, and other HV/High risk pursuits” – Link.
TIG (Tungsten inert gas) is also known as G.T.A.W (gas tunsten arc welding) or sometimes helearc which refers to the use of helium in the origanal desigs, and confusingly a patanted design to spiral air in plasma cutting torches (a compleatly different proces)
TIG welding is used when a very accrate and neat weld is required. it also has other advantages, for example Copper, titanium and aluminium can be welded. – Link.