Below is a guide on the 1 artifact, 3 coins and 1 workbench that can be found during The Forward Base chapter in The Last of Us Part II.
Coin – California
When the chapter starts, head up the small flight of stairs on the right side to find the coin near the rail.
Coin – New Mexico
This coin is located on a green crate next to the porter potties after checking in.
Workbench
The workbench can be found in the first big white tent to the left of the path after checking in.
Coin – South Carolina
After entering the apartment building where Isaac is, take a left to find 3 picnic tables. The coin can be found on the far left table.
Artifact – WLF Interrogator Letter
This artifact can be found in the same room as the above collectible on a wooden table.
Click here for the next guide on the collectibles in Hostile Territory!!