RainLover writes:

I'm building a sculpture and the client wants to be able to turn it if
he wants. It'll weigh around 300 lbs.

Would regular steel work if it was greased up well? It would
probably never get RE-greased, but then again, it's never going to
spin at 100 RPMs.. just be shifted around from time to time.

Whatever you use, I'd worry about it getting gummed up with crud
if it's not being exercised regularly.