Buiding an airtank

Unless you are having a pulsation problem or overheating your compressor, you won't accomplish much. The tank pressure is only going to be as high as the pressure of the compressor, which is probably around 20 to 30 psi. It will act as a reservoir for the air at the max pressure of the compressor, but unless you get a HUGE tank you'll only get a few minutes of painting before it drops below the required pressure.

If you want to do it, what you will need is:

1) A pressure line from your compressor to the tank. I'd use some sort of quick-disconnect fittings so you can disconnect it easily. 1/4" NPT threads are the most common, so if your compressor already has an outlet that size you won't need any sort of adapter.

2) A Check valve in the line from the compressor to the tank so air can only flow one way (compressor to tank).

3) An outlet on the tank for your airbrush. This needs to be a self-closing fitting so that if you unplug your airbrush you won't loose all your air.

4) A drain cock on the tank. As air is compressed moisture is going to get squeezed out and collect in the tank. You need to be able to drain this regularly.

5) Optionally, a pressure switch. This will turn on the compressor when the tank pressure falls below a preset level.

MusicCity has some good points there.
I think that a tank could possibly give you enough reserve with the compressor left running to keep your air pressure up longer. A lot of these small compressors put out 20-30 psi static pressure but as soon as you hit the airbrush trigger they drop to 10 psi.
Is this the reason you want a tank or was it something else?
If you are having pulsation problems from a diaphragm compressor then the tank will smooth out the airflow.

Mike

I want to regulate the pressure actually and have a resevoir. I dont like my brush being connected almost directly to the diaphram. I dont have a pulsating problem at all but I am using a pos AB til I can order my Badger and would like to help my POS by lowering my pressure a tad since it tends to blow a clouds of paint no matter what my thinner ratio is...can you guess what my pos ab is??? Anyways I saw this as a stop gap til I can afford my $400 compressor I want.
So outside of constructing the mentioned tank I can just put on a regulator and do it that way to right?

Yes a regulator should do what you want.
What $400 compressor are you saving for?

Mike

I dont know who makes it I saw it online and at my lhs and my lhs has it cheaper...go figure after my AB disappointments there. Its basically like a badger or iwata mini custom mounted on a tank with all the goodies.

Jeff,

Shop around before buying it because at that price you can get a Badger Million-Air. I recently received one and it is nice.
Have you ever been to Coast Airbrush? They are in Anaheim.

Mike