Ist, I am always a little leary of CAD drawings and no actual pics. Probably means the designer didn't actually print and try his own design. Because a pic would be the FIRST thing I did after printing.
Next he wants someone to print them out and tell him how it goes. If he had a working design he would be telling us "how it goes" in pictures and video.
Then all of that mass becomes a giant sail while flying. It doesn't make for the best flying experience and they probably are going to show in video.
Finally, I played with trying to make a float for a scratch built multirotor I have. Judging from my experience, IF, and thats a BIG IF from 3D printed plastic, If that floats, it will be very top heavy and tip over at the slightest wave or even hard landing. But that might be better than heading for Davy Jones's Locker. Lots of folks have posted getting all or most of their Phantom working after a dip in the pool/lake/river. Even if it floats upside down, that would be better than never seeing again.