material for reflectors

[Rikko]

Stainless is nice but will likely corrode. There's a good thread on RC about it - I think there's only one "grade" of stainless that actually won't corrode under saltwater. Type 330? Does that sound remotely like a steel grade? Wish I had the link for ya.
Aluminum is pretty popular and from the sounds of it doesn't corrode all that fast (and is cheap enough to be disposable when it does). The metalworkers I've seen post have polished it themselves to get it reflecting well.