{
  "Only stack furnaces in Building Privileged zones": true,
  "Permissions & their amount of stacked furnaces allowed": {
    "furnacestacks.use": 2,
    "furnacestacks.vip": 4
  }
}

Configuration:

{
  "Only stack furnaces in Building Privileged zones": true,
  "Permissions & their amount of stacked furnaces allowed": {
    "furnacestacks.use": 2,
    "furnacestacks.vip": 4
  }
}
Language:

{
  "MaxStackAmount": "You are trying to stack more than {0} furnaces!",
  "OnlyStackFurnaces": "You can only stack electric furnaces!",
  "CeilingBlock": "A ceiling is blocking you from stacking this furnace!",
  "BuildingBlock": "You need to be Building Privileged in order to stack furnaces!"
}