What about making something light and buoyant that is actually a nautical symbol of something that is heavy and certainly not meant to float ☺
I designed an anchor to be used as a float / buoy for your boat keys. When going out on a sunny day, taking the boat for a spin, you don’t want your fun to get spoiled when you accidentally drop your keys in the water.
The design is fully hollow and all the walls are 2.25 mm thick, to allow this to be water tight.
Use a total of 5 perimeters and 5 or 6 top/bottom layers and 0 procent infill