Jim Weir wrote...

Oooookay, let me try again.

What NONLUMBER bench tops have you ever seen or considered that might
work?

NONLUMBER? For a 2'x6' top? Shoot, Home Despot has marble for, like,
$70/sf. Steel's probably too expensive too. If it doesn't have
to be super rigid you might try 0.064 AL. The short answer
is there probably isn't anything readily available and cheap.
Bricks, maybe, or patio pavers.

Me, I'd use plywood and slather epoxy on it. That's what
I do already. Whenever I have leftovers I just dump it on
one bench in particular and squeegee it over the top.
But that's not what you asked.

Dave 'hardtop' Hyde