Any way to duplicate the /pf feature, but reverse it? So maybe a /pu command, that will take some CN, and turn a stack of stone BACK into Cobble? Or maybe, rather than a reverse furnace (this would let you create ore blocks from ingots, which would decrease value of having an actual ore block), maybe it can break things, too? Wooden stairs become, say, 4 planks? (not a straight 1:1 change for what you have and what it takes to make it, but more efficient than breaking it manually, as far as stairs go) Theoretically, you could add furnaces, chests, workbenches, doors, trapdoors, cobble/wood stairs, cobble/wood slabs, fences, ladders, so on. A more advanced version could break Dispensers and Pistons to get some of the resources back, maybe.
But my main thought, was that I used to keep massive amounts of Cobble handy, slowly smelting it into Stone. I kept Stone for the New Sanctum walls, and eventually got my Lava Furnace, so I now smelt and sell all my stone. But even if I have some Stone on hand, I don't have Cobble. So I was thinking, what about a simple way to take Stone, and smash it back into Cobble, so I can use it for Levers and Pistons and such. (but obviously, more effective than placing and breaking each block, and also without tool damage)
So I suggest the Pulverizer, a basic simple counterpart to the Personal Furnace.