DArkRP - Printer Groups

So on a server I manage we have 4 types of money printers. Steel, Homemade, Golden, and Regular.

I want to make it so that I can group them together and make the max of 4 total in any combination. How is this possible? Do I use a table or …

Whenever one of these is spawned, add a value to a counter specific to the player. Whe none is removed, remove from the counter. If the player hit his limit, restrict any more printers.