These are the main parts of a basic potato gun.  The gun we built uses this basic model, repeated four times.  Then we mounted everything on a rack to hold all the components.

Above is a diagram of how the fire control systems are wired.  The diagram is a little more basic than the actual control box is, but can be used to wire simple guns.  Our potato gun has a "remote control".  It is not wireless, but it is about 6 ft away from the gun.  We call this the "Box".  The Box contains a series of safety switches, and controls the when the gun will fire.  We felt this was safer, because if something were to go wrong, you would be far enough away from the gun that you wouldn't get hurt.  If a potato gun explodes or malfunctions the results can be deadly.  These are usually a result of faulty craftsmanship, or plain staidness.  When we built the gun we decided to install all the electronic components in an empty IBM computer case.  The case is mounted on ball bearing casters under the barrels, so that we have access to it.  Unfortunately we do not have pictures with the computer mounted underneath.