You can build a air compressor tank out of aluminum, but I would buy one and not try to make one yourself.
I make tanks all the time for boats...out of steel, aluminum and even plastic, but I never test them to more than 5 psi. That is a huge amount of pressure once you do the math. These tanks expand more than you can imagine, often busting the plastic tanks and getting pin hole leaks in the aluminum ones. Now can you imagine building something to withstand 120 si. Please let the experts do it on account of safety.
I have no intention of traveling from birth to the grave in a manicured and well preserved body; but rather I will skid in sideways, totally beat up, completely worn out, utterly exhausted and jump off my tractor and loudly yell, "Wow, this is what it took to feed a nation!"