Maybe not square but this might be an idea to float lights. easy floating pool lanterns DIY by using Styrofoam squares, poking a dowel rod into each corner of the square, and then putting tissue or wax paper around the rods
I love this color! "If you have any body of water near your wedding, these floating paper lanterns would be amazing! maybe change the color of the lantern to a more neutral color, whatever colors are in your wedding palate!
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