This is the gun's power supply. We recommend using a 7.2 volt rechargable
battery pack, using either nickel cadmium (Nicad) or nickel-metal hydride
(NiMh) battery cells. NiMh have the advantage over Nicads as they don't
suffer from the "memory effect." The are however slightly more
expensive than Nicads.
It is possible to purchase a battery pack pre-assembled, as used in radio
controlled cars. This has the advantage of being very convenient and easy,
but can tend to be quite bulky and fixed in shape.
We more often use AA batteries, and assemble them into a plastic battery
holder. This allows long, skinny configurations, or short fat configuration.
Depending on the design of your gun either could be more suitable.
A further option is to purchase "solder-tab" batteries. This
allows you to position the batteries anywhere you like, in any shape you
like, and connect them together by soldering wires. This gives maximum
flexibility but takes additional time.
For most people 6 x AA batteries in a plastic holder is the best option.
Some examples of battery installations and packs:
Remote controlled car pack
6 x AA solder tab