There are 4 supply boxes around the map that contain Copper.
An alternate and potentially faster method is to kill Griff Guards. One method is to find a Griff Guard near a doorway, kill the guard, enter the door, exit, and repeat. This is also a very efficient way to farm copper. A Hoarder Mod equipped will greatly expedite the process.
Ton Luong, one of the Kickstarter hostages, can be rescued on the East side of Area B. Rescuing Ton Luong counts towards the main objective hostage count.
A Titan Plate can be found to the East of Ton Luong's location by equipping a Paratrooper Mod and jumping East from the top of the nearby tower. Alternatively, one can use an automatic weapon with a large magazine to make the jump.
Using the Transceiver at the beginning of the area, one can hop onto the supply box that is summoned and jump over the truck that blocks the path to the West.