Its actually easier for me to work with metal than wood due to my profession. I've never cut a board in my life haha.
The plate would be powdercoated black which should help with moisture.
I'm not worried about rust stains on the countertop since I could probably just buff them off.
If I go with plywood how thick and what kind? I am completely ignorant of woodworking and carpentry.
Hello; Powder coat will be better than paint. You must have the capacity to bake a fairly large bit of plate.