Painting the Town

Talk to Abbot who is painting the wall in the northern side of Diamond City. He'll ask you to retrieve some paint in Hardware Town. You can also haggle the reward, up to 200 caps if you successfully passed all three Charisma speech checks.

Head to Hardware Town and clear the enemies as you make your way to the western end of the warehouse. You'll find the paint mixer there. Collect all blue and yellow paint cans then use the paint mixer to produce 3 green paint cans. Leave the place and report back to Abbot. He'll then ask you to apply the paint on the wall. Use the green paint then talk to Abbot again to complete the quest and get the bonus for using the green paint.