Here’s a second attempt of a “modular face”, this time for my Endor Rebel Trooper Helmet MOC.
It’s Captain Rex face, when he fought in the Battle of Endor, which saw the first death of Emperor Palpatine, the redemption of his former Jedi General Anakin Skywalker, and the destruction of the second Death Star.

To use this face with the Endor Rebel Trooper Helmet, you need to skip steps from 82 to 90 of the Helmet instructions and follow face instructions at the end

Inventory has only the parts for the face!