This suffix title "Guild Hall Constructor" is granted by the quest "Construction Materials" as part of the lead-up to the introduction of Guild Halls in EQ2. You achieve this by completing 30 construction materials quests.
To set suffix and/or prefix titles after you earn them:
- Press C to open the Character sheet
- Click on the Options tab
- Locate the drop down to see all of the titles you have earned and select the title you want to display.
- You can see the title displayed with your character's name at any time zooming out and by pressing F1 to target your own character.