I need to make six bronze portlight frames (8" x 16") for my boat. These are just flat frames that would be 3/16" thick. I have a friend who has a CNC mill that could cut these out. So I need to buy the flat 3/16" sheet stock. What alloy should I look for? I've played with naval bronze but it seems really hard, just need something that is millable and appropriate for a salt water boat.
They would look like this (computer image).