A little more than a week ago I decided to throw together a tool to test my car for vacuum leaks. Here is the thread in which I described what was made:
The list of parts is there, but I've also decided to make a bunch in case people want to buy one pre-made. My air compressor has a built in regulator, but just in case I will be making two different flavors: one without a regulator and one with an attached regulator. I see this as an invaluable tool that I keep in my car at all times, and it can be used on pretty much any car. It will come ready to be attached to a compressor via a quick detach plug unless otherwise specified.
Without regulator: $25 shipped to lower 48
With regulator: $30 shipped to lower 48