After you print the battery box you will need two male F connectors (quick disconnects, flat). Insert wire through the holes in the bottom of the printed box. Crimp and solder the wires to the lugs. Apply a dab of hot glue to the base of the connector and pull the wire back through pulling the connector into the hole. Twist to align to the blade openings in the battery.
This should help you visualize the battery box:
Fabricate a small fuse holder using two female F connectors and an ATX 7.5a fuse.