I can't find any reference to this exploit anywhere, it's so obvious that I can't believe it isn't known.
If you get a Router, or probably any other device that can stuff into the output slot, to fill the output of a furnace with charcoal, you get experience for pulling it out. Rig up an Obsidian Pipe to put it back in the device that does the stuffing, and you can just pick up and drop charcoal for a few minutes and get yourself tons of XP.
If you get a Router, or probably any other device that can stuff into the output slot, to fill the output of a furnace with charcoal, you get experience for pulling it out. Rig up an Obsidian Pipe to put it back in the device that does the stuffing, and you can just pick up and drop charcoal for a few minutes and get yourself tons of XP.