• Safe House
• Timefall Shelter
Climbing Anchor (must then plant and use one in the outside world)
Ladder (must place one in the outside world)
Roadway (just one for the trophy)
Hold L1 to bring up the compass and then hit triangle. You must build one of EVERY sign for the trophy. These cost nothing to make so choose a spot away from where people may not find them and spam build them.
You could also be helpful and build them to warn other players or aid them, this is likely to generate likes.
EDIT: Since it has now been confirmed by two gamers, I'll add that there may have been a patch since I unlicked this. Building a few unique signs will still unlock the trophy.