Tube notcher- makes the job of building tubular framework a lot easier and stronger!
Good old angle grinders for smoothing / grinding and for cutting. I use abrasive flap wheels for grinding as they are more controllable than grinding wheels and for cutting I use paper thin cutting discs as they cut quickly and waste far less metal.
Pillar drill, whist not essential it makes drilling accurate holes so much easier.
Welder. For a begineer a MIG welder will make the task of welding a lot easier.
Auto dimming weld mask. Buy the best you can afford is my advice. I went for years using cheap auto dimming masks and then eventually decided to splash out on a decent one. The difference is amazing, the 'new' mask is more comfortable, is better balanced and most import the screen is far more sensitive and yet allows me to see the work piece more clearly. Money well spent.
Welding table. Another non essential but it does make welding easier as the earthing clamp is attached to the table which then becomes 'live'. The table folds up so can be stored out of the way when not in use and has wheels to make it easier to move around. The table top is on a pivot so can be tilted through 90 degrees so items can be left clamped in place and then the table top rotated to get at weld areas.
