The floats need to vary equally between specific gravity of about 1.0~1.2. Specific gravity is adjusted by blending light and heavy density matter in an appropriate ratio.

The lighter material is glue for melt guns. The specific gravity is less than 1.0. The heavier one is a free resin. It softens when warmed with hot water, etc, and hardens when cooled

By boiling and mixing these materials, we can create a material with a certain specific gravity. However, the produced material is not completely homogeneous, so by rounding this material into pellets, we can make pellets is with different specific gravity.