I'm getting ready to build a new float for the lake, to replace one I built in 1996. It was built with untreated wood and cheap paint and hardware. This one will be made from treated wood and the best paint and hardware for fresh water I can get. Hopefully, it will last until 2030.
It will be slightly larger than 12 feet by 8 feet. Here's the treated plywood.
And here are two of the four styrofoam logs that I'll cover with fiberglass wrap.