I need a large ultra high vacuum chamber (sub 10^−6 pascals). This means thick stainless steel walls and solid welds, so no molecular leaks. I would like it to be cylindrical or cubic (not spherical).

Problem is, these things are FUCKING EXPENSIVE. Not to mention all the flanges/extras you'd have to buy to get it up and running.
How can I build up my skills to weld one of these things myself?