How to make a resource generator?

[WolfClaw114]

I want to add in an object into my mod which will create resources over time e.g. food, water, ammo ect.
I assumed i could alter a water purifier to produce something else but that ended up not working, didn't even see a reference for purified water within it. 

Is there another way, or tutorial i somehow missed which goes through the process of creating a resource generator?

[niston]

F4MS Factory was written to do this.
There is a demo mod showing how to use it.