in my opinion stanless is the go easy to work with look great can be shiny can be mashined look or you can paint it and every place has it mandrel is good cause you can buy it at any decent fabricator,zaughst joint
i have doen all of mine in stainless always and when you are putting 20 psi thru it you can clam it down as hard as you want and the hoses wont blow off it would be the same price as ali