Now I got to start thinking ... Hmmm. I would fabricate the framework out of suitable steel and send it out to be galvanized. I would use two opposed weights on the lake bottom to prevent the station from spinning or winding. Probably use a center steel bar on the underside and inline with the weights that would allow the chain loop move with the current and wind to prevent flipping. I envision about a 6' X 6' floating island filled with soil but would require some sort of lip to prevent wave action to wash soil out. Another choice would be to have rocks on the soil surface like pea gravel covered with river rock. Or even castle-like walls that would allow plants to grow outwards. I'd like to use some aquatic plan that would spread and cover a reasonable large coverage area. 40 foot radius or larger. Is there such a thing? I may need additional "satellite" stations for extensive coverage. I am aware that I would have to calculate floatation to which is no problem. Any construction ideas or experience with similar projects? Can you recommend a suitable spreading plant?