This achievement will require you to find Bruno's three tools that are scattered across Balboa Island.
Bruno's Saw can be found inside of a locker at the base of the pathway that leads up to relay stations 4 and 6. Be careful because taking the saw will cause the bear down the hill to become aggro.
Bruno's Hammer can be found on a shelf in relay station 4.
Bruno's Wrench can be found on a table in relay station 6.
Once you have all three tools, head to the ranger's station and place them on the tool board. This will cause the board to fall to the floor and you can pick up the note behind it which will grant you the achievement. This note is also needed for the "Balboa Historian" achievement.