You need to build the thing up yourself, just like we did. You'll need a nitrogen bottle, hi-pressure hose and valve, a tube that will hold pressure, parachute rigger's needles, IBM cards (cut into cones and glue to the end of the needles), and a valve to regulate discharge.
Where the rats in the open, out in a field, in a hangar?
In the hangar. We had the absolute WORST rat problem you ever saw in our hangar.