The Apply Base feature creates a flat surface on the base struts to ensure platform adhesion during printing.

Use this feature when you want to adhere your lattice directly to the platform.

Without a base, the platform-facing surface of the lattice just lightly touches the platform at each strut.

This will likely lead to under-adhesion (part does not fully adhere to platform).

Applying a base extrudes the cross section of the struts down to Z-zero (represented by the grid in the Design Engine).