Nerf RapidStrike Battery mod

My initial plan was to replace the standard battery box with something that can hold a 6-cell 7.2V NiMH/NiCd battery pack commonly used in RC cars, but it was too short.

I remodelled intofocus's box (which I really liked because of the way the connector is made) to incorporate the front lid (I removed the bottom screw-hole for easier printing and it does not really need the 3rd screw), still I had a hard time fitting the NiMH pack into the box (it was the Tamiya connector giving me problems)

In order not to disappoint my son, I went for a quick solution, which was to connect a tamiya contra plug to the battery box (so there is no battery in the box now), I insulated the copper wires with PVC ('electrical') -tape ,drilled two small holes for the wires, and put a small knot in the wires to prevent them from being accidentally yanked out.

The battery itself is mounted externally using a clip that can slide onto the side 'picatinny' rail of the Nerf blaster. The NiMH pack is