Underwater Floater #MakeItFloat

thingiverse

People will see essentially a buoy that has a compartment specifically for putting quarters into the shaft. There's a hole in the top, going straight through the air compartment above. The upper part of this floating device is carefully designed with displacement in mind, and since the quarters are nearly six inches below the water surface, it results in a low center of balance and verifies that the floater won't capsize easily.