I got a nice welder from my wife Sunniva this christmas that was flux core only. After reading a bit about welding I decided to check if it was possible to convert my welder to MIG with gas shielding (Argon or Argon/CO2). This is attractive since you could make much nicer welds, poisonous fumes are minimized and you should in theory be able to weld both stainless steel and aluminium.
After opening up the torch I found that it contained a gas valve that had a threaded hole. I bought a small bottle gas kit for a different welder, made threads on the straight part of the quick coupling and bought a longer nylon tube for the quick coupling with the same diameter. Now I am able to do both flux core and gas shielded welding.