Maybe this quick sketch will explain better.
The eggcrate pattern is cut into the bottom of a styrofoam panel. The depth of the cut is the same as the eggcrate thickness so it flush mounts to the bottom. GE Silicone 1 is put in the cut pattern and the eggcrate is pushed in. Additional silicone is applied to the eggcrate to make sure it does not separate from the styrofoam.

The eggcrate pattern is cut into the bottom of a styrofoam panel. The depth of the cut is the same as the eggcrate thickness so it flush mounts to the bottom. GE Silicone 1 is put in the cut pattern and the eggcrate is pushed in. Additional silicone is applied to the eggcrate to make sure it does not separate from the styrofoam.


