Created on request. If a player is in a furnace, this will prevent others from using it while they have the furnace inv open.

Commands

/NOSY UNLOCK
nosyfurnace.unlock
Lets you manually unlock a furnace.

/NOSY LIST
nosyfurnace.list
Show all currently locked furnaces

/NOSY SUSPEND
nosyfurnace.suspend
Disables functionality, in case you want to collaborate with someone in a furnace. It's a toggle, so do it again to re-enable furnace protection. This only applies to the player that runs the command, it isn't global.

/NOSY MAXTIME seconds
nosyfurnace.maxtime
Sets a timeout in seconds for furnace locks.

/NOSY RELOAD
nosyfurnace.reload
Reloads configuration

It defaults to no time limit. If you enable a time limit, you can use %timeleft% in the list-data and locked messages to return the amount of time left in the lock in a HH:MM:SS format. If there is a clamor for it, I can add configurable time strings but I doubt it'll be that big a deal so I didn't worry with it.