You will need a tank, compressor, air lines (soft lines are SO much easier than bending hard lines), a manifold, pressure switch and check valve. Also wiring for the compressor including a switch and relay, possibly a pressure gauge.
There are several ways to go about this, depending on how YOU want to set it up.
The pressure switch you buy will depend on the compressor and the tank. Basically you have to figure out how much psi the tank can hold, and how much PSI the compressor can reasonably create in the system without overheating.
If I were doing on board air right now...
We'll start with the tank. Plugged into the tank would be an air manifold, how many outlets on it would depend on how many airlines you want. Things plugged into the manifold would be;
1) Pressure switch (this sends a signal to the relay for the compressor to turn it on below X psi, and off below Y psi)
2) The line coming from the compressor, with a check valve close to the compressor. This prevents the air from bleeding off back to the compressor valves.
3) Air lines going to where ever you decide you need them. It wouldn't be a horrible idea to put a regulator here with a water drain or something as well, although the regulator isn't really necessary.
2006 F150 FX4 Super Crew - Bilstien 5100s leveled 2", 35" KM2s, 4.56 gears, Detroit locker, Eaton E-Locker, Traction Bars, AEM intake, Xcal 2
2010 VW Golf TDI 6MT