You can build it yourself.
Take a large underground sprinkler box, the one with the removable top, usually plastic. Airline from compressor goes in, you make a manifold with ball valves going to each diffuser. Turn on or off each diffuser there. If you want to get fancy, you can put in a "T" to add a low pressure gauge for each diffuser to monitor their performance. Typically 0-30 psi range.
Box is sunk into the ground with the top flush with the top of the ground so you can mow over it.
An image I grabbed from the internet. If I were to make my own, I'd make it from plastic and have brass ball valves.
