Thanks! The sink is from the salvage yard and I painted the bottom. The wooden base was a work bench the client had.

Thank you for taking the time to answer my question. Looks like I might have to go salvaging. ;) Again, LOVE this ... and the inspiration.

Honestly, that was the first thing that got my attention.
I'm in process of redoing a small (5' x 8') bath and I'm figuring in some galvanized corrugated steel for the shower and walls. I may spot-treat with vinegar to get a bit of 'rust' on it, then seal. The current sink I have built into an old wine barrel - the basin is a galvanized bucket and the spigot is a hand-pump with pex piping I ran up through it.
After seeing this design however, I may save the barrel sink for the attic bath (that I have to design/build) and do something like this instead. :)

What gauge of galvanized metal did you use for the walls?

Not sure what the gauge is, but it is a roofing material from the local hardware store.