I guess you guys already know that "Surtling – infinite core and coal farm" well.
But do you know Greydwarf – infinite wood and stone farm too?
Oh, I searched and found this just now
okay but here is the other simple idea, also from Korean community. (5.March)
Build 3~5 Bonfire near Greydwarf spawner, and put some wall to lock them in.
Use a door instead of one of that wall, for entrance/exit
Just wait for some minutes and you will get free wood and stone 🙂