Looks like it is milled from one piece of aluminium or steel. STrong
This applies to all home air stations but it can be dangerous.
This thing is great. I have an old scuba tank and I can get it filled for the price of one of my paintball tanks but I can fill my air tank about five times. It is easy to use, and does what it should. It isn't complicated but any air filling can be dangerous, so be careful.
Overall this is a great filler. I even got the local scuba shop to let me use it to fill my 4500psi tank. But be careful it is dangerous like any air filling equipment, but that does impact my review because it does a great job and definitely minimizes my chances of having a problem.